中国生态农业学报(中英文)

Effect of combined application of organic and inorganic fertilizers on soil nitrous oxide emission in maize-cowpea systems in central China

SHUAI Yanju, LIU Tianqi, CAO Cougui, LI Chengfang

2018, 26(12): 1763-1772. doi: 10.13930/j.cnki.cjea.180191

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Abstract:
Nitrous oxide (N₂O) is an important greenhouse gas that causes stratospheric ozone destruction. Application of chemical nitrogen fertilizers in upland cultivation systems is an important source of atmospheric N₂O. It is important to determine the effects of nitrogen fertilization on N₂O emissions in upland field in Central China where the relative researches is less conducted. In this study, soil nitrification and denitrification rates, N₂O emissions and crop yields were investigated under application of organic and inorganic fertilizers with the same amounts of N in the field. Therefore in 2017, a field experiment was conducted to investigate the effects of different nitrogen fertilizer sources[inorganic nitrogen fertilizer (I), organic nitrogen fertilizer (O) and inorganic plus organic nitrogen fertilizers (I+O)] on nitrification rate, denitrification rate, N₂O emission and crop yield under a maize-cowpea cropping system in Central China. Emission of N₂O was measured by the static chamber approach and the rates of nitrification and denitrification measured by Barometric Process Separation (BaPS). The results showed that the rate of nitrification ranged from 130.90 μg·kg^-1·h^-1 to 340.37 μg·kg^-1·h^-1 in maize season, and from 145.11 μg·kg^-1·h^-1 to 348.75 μg·kg^-1·h^-1 in cowpea season. Application of organic nitrogen significantly affected soil nitrification rate. Compared with I and O treatments, I+O treatment significantly reduced soil nitrification rate respectively by 28.74% and 13.96% in maize season, and by 24.66% and 13.28% in cowpea season. However, no significant differences were observed in the rate of denitrification among three treatments. Nitrogen fertilization significantly enhanced N₂O flux, with N₂O flux peak observed immediately after nitrogen fertilizer application. The combined application of inorganic and organic nitrogen fertilizers markedly influenced N₂O emission. The mean N₂O flux in maize season under I+O treatment was (279.54±116.58) μg·m^-2·h^-1, which was 33.44% (P < 0.01) and 32.29% (P < 0.01) lower than that under I and O treatments. In cowpea season, mean flux under I+O treatment[(188.07±57.63) μg·m^-2·h^-1] decreased significantly by 27.00% and 15.14%, compared with that under I and O treatments. Moreover, compared with I and O treatments, I+O treatment significantly reduced cumulative N₂O emission respectively by 33.51% and 32.51% in maize season, and by 25.77% and 15.04% in cowpea season. However, there were no significant differences in N₂O flux and cumulative N₂O emission between I and O treatments. Linear correlation analysis showed that N₂O emission was closely related with nitrification rate. Yields of maize and cowpea varied among different treatments and I+O treatment had the highest yields of maize and cowpea. Yield of maize under I+O treatment was 1.71 and 1.23 times that under I and O treatments, and yield of cowpea under I+O treatment was 13.4 and 1.17 times that under I and O treatments, respectively. No significant difference was found in cowpea yield between I and O treatments. Our results suggested that combined application of organic and inorganic nitrogen fertilizers effectively reduced soil N₂O emissions and increased crop yield in maize-cowpea cropping systems in Central China. The study had important implications for high-yield, low-carbon crop cultivation in China.

Heat conduction law of hydroponic nutrient solution as heat storage medium

MA Yujing, WEN Xiangzhen, DU Liwen, LI Yaling

2018, 26(12): 1773-1780. doi: 10.13930/j.cnki.cjea.180359

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Abstract:
In order to grasp the characteristics of heat transfer of hydroponic nutrient solution as heat storage medium and the related heat storage and preservation performance, nutrient solutions of leaf vegetable production systems were used for experimentation. The experiment was conducted at the solar greenhouse of Agricultural Engineering Institute of Shanxi Agricultural University. In this study, SH-16 road temperature inspection was used in leaf vegetable production systems and sensor elements placed at several different depths of different positions to monitor solution temperature. The regulation of temperature change of nutrient solutions in the system under porous planting plates were discussed. The experimental results showed that temperature change in nutrient solution at different depths were significantly different. The largest amplitude of temperature variation of nutrition solutions was at surface layer. The deeper the nutrient solution, the smaller was the variation. The highest temperature of nutrient solution in autumn decreased rapidly with increasing nutrient solution depth, and happened at 14:00, 16:00, 17:40 and 20:00 for the solution depths of 0 cm, 5 cm, 10 cm and 15 cm respectively. Based on the daily range of temperature at different depths, nutrient solutions were divided into three temperature layers-heat exchange layer (daily range of temperature > 3℃), heat buffer layer (daily range of temperature of 1-3℃) and heat stability layer (daily range of temperature at 0-1℃), which were located in the solution layers of 0-5 cm, 5-10 cm and 10-15 cm, respectively. When the nutrient solution depth of leaf vegetable production system was 21.5 cm, the relationship between daily temperature difference and solution depth (0 cm, 5 cm, 10 cm, 15 cm were expressed as 1, 2, 3 and 4 in the function) was described with the logarithmic function y=-2.619lnx + 4.215 2. That indicated that daily temperature difference at 20 cm below solution surface was 0℃. The above results indicated that energy was conducted on a layer-by-layer basis in the nutrient solution of hydroponic system.

Revisiting crop water production functions in terms of cross-regional applications

LI Zhongkai, LIU Hu, ZHAO Wenzhi

2018, 26(12): 1781-1794. doi: 10.13930/j.cnki.cjea.180369

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As populations grow and demand for food increases in the world with limited water supply, the production of more food with less water becomes a significant global challenge facing us in the decades to come. Crop water production function (CWPF), i.e., the functional relationship between crop yield (Y) and evapotranspiration (ET), is the link between water use and crop productivity in crop models. However, most of studies on CWPF have been based on local observations and therefore results derived have not been accurate and not applicable to other regions. Most recent advances in CWPF researches were reviewed in this work, including related theories, models and field experiments. It showed that CWPF was affected by many factors, including climatic conditions, irrigation strategies, soil types, nutrient levels, crop species and even crop cultivars. However few theories had so far provided a comprehensive framework connecting these factors to CWPF. Because of the lack of solid physical foundation and reliable theoretical support, observation-based models were limited in providing beyond local prediction for a given type of crop. Also the mechanistic models and more complex crop models that were largely based on carbon assimilation processes were difficult to apply in practice because of far too many parameters. Through summary analysis of published work, a total of 592 sets of field data were screened from 41 literatures. We found that although the data distribution was relatively sparse, linear correlations (r²=0.34) existed between yield and evapotranspiration for wheat. However, similar correlations were not detected for corn, cotton and rice, probably due to the small amount of available experimental data. Using meta-analysis, a new method of modification of CWPF was proposed and tested in order to improve the performance of CWPF for cross-regional applications. It was found that the statistical method used was good to get better and more stable CWPF for given species across different cultivation environments (r² increased from 0.36 to 0.75), when seasonal precipitation (P_rec) and accumulated pan evaporation (E_Pan) were incorporated. Our results showed that the functional relationship between Y and ET×P_rec/E_Pan was more universal, compared with that between Y and ET in cross-regional application. Although more reliable and even flexible CWPF models were derived by the inclusion of other calculation algorithms in this framework, we argued that mechanistic models were needed in future extrapolations of measured relationships beyond simply assuming that they were statistically significant. Future work needed to focus on:1) strengthening theoretical interpretations of the revised results; 2) testing the potentials for modification to accommodate other crops; 3) considering the growth stages in CWPF to improve its potential for cross-regional applications.

Effects of cow dung and biochar on root growth, soil properties and nitrogen utilization of apple

WANG Fen, LIU Hui, FENG Jingtao, TIAN Ge, LIU Xiangyang, GE Shunfeng, JIANG Yuanmao

2018, 26(12): 1795-1801. doi: 10.13930/j.cnki.cjea.180394

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Two-year-old 'Fuji' apple (Malus domestica Borkh. cv Red Fuji/Malus hupehensis) trees were used to study the effect of cow dung and biochar on soil properties, and apple root growth, nitrogen uptake and utilization using ¹⁵N isotope tracer technique. The study aimed at providing reference for rational fertilization and sustainable apple development and production. There were 6 treatments in the study-no cow dung or biochar (CK), 100% cow dung (T1), 75% cow dung + 25% biochar (T2), 50% cow dung + 50% biochar (T3), 25% cow dung + 75% biochar (T4) and 100% biochar (T5). The results showed that combined application of cow dung and biochar improved soil physical and chemical properties, and increased soil contents of organic matter, alkali-hydrolyzale nitrogen, available phosphorus and available potassium, but reduced soil bulk density. The soil contents of organic matter, alkali-hydrolyzale nitrogen, available phosphorus and available potassium decreased gradually with decreasing cow dung proportion, and they were highest under T1, which increased by respectively 97.31%, 19.01%, 24.37% and 32.73% over CK. There was no significant difference between T1 and T2 in terms of the contents of the variables. Soil bulk density decreased with gradual increase in biochar proportion. The difference between T4 and T5 treatments was not significant. Soil bulk density under T4 or T5 treatment was significantly lower than that of CK and T1. Bacteria population was highest in rhizosphere soil, followed by actinomyces, and fungus content was lowest. The addition of cow dung and biochar significantly increased the number of bacteria, actinomycetes and fungus in rhizosphere soil. The population of bacteria, actinomycetes and fungus was highest in T2 treated soil. The cow dung and biochar mixture also promoted apple root growth. Root tip, root surface area and root activity were highest in T2 treated soil, with respective increases of 47.90%, 33.47% and 44.67% over that of CK. Compared with CK, the cow dung plus biochar significantly improved the Ndff value, total nitrogen and ¹⁵N absorption of various organs of apple. It also increased ¹⁵N utilization and residual rate, while reducing ¹⁵N loss rate. The utilization rate and the residual rate of ¹⁵N were higher under treatments of mixed cow dung and biochar. Single application of cow dung or biochar was second and CK treatment the lowest. The loss rate of ¹⁵N showed the reverse trend. T2 treatment showed best with the highest ¹⁵N utilization rate and residue rate and lowest ¹⁵N loss rate. Under T2 treatment, while ¹⁵N utilization ratio increased by 5.51%, ¹⁵N loss rate decreased by 14.52% compared with CK. Comprehensive analysis showed that the 75% cow dung + 25% biochar treatment (T2) had the best effect on apple root growth, soil characteristics and nitrogen absorption and utilization.

Effects of mulching patterns on root growth and soil environment of Lycium barbarum

XU Shengrong, ZHANG Enhe, MA Ruili, WANG Qi, LIU Qinglin, WANG Heling

2018, 26(12): 1802-1810. doi: 10.13930/j.cnki.cjea.180305

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Lycium barbarum is the main commercial crop across arid lands in northwestern China. In order to further understand the effects of different mulching patterns on root growth and soil environment, a mulching experiment was conducted at the Agricultural Demonstration Site in Gulang, Gansu Province (37.30°N, 103.29°E). The experiment consisted of four treatments —— plastic film mulching from spring of the second year (PMs), plastic film mulching from autumn of the first year (PMa), stalk mulching from spring of the second year (SMs) and stalk mulching from autumn of the first year (SMa). Root physiological characteristics and distribution, soil water storage and temperature of three-year-old plants of 'Ningqi 1' L. barbarum were studied. The results showed that both plastic film mulching and straw mulching improved soil water storage, and autumn mulching was better for winter soil water storage, which increased to 117.1% and 114.4% of that of CK (no mulching), respectively, in the next early spring. PMa and SMa respectively increased average temperature of soil by 18.0% and 7.1%, while PMs and SMs increased average temperature of soil by 6.4% and 2.3%, compared with CK. Both plastic film mulching and straw mulching improved annual specific conductivity of root, and the change in specific conductivity was most significant under PMa, reaching 109.95% of CK. Also change in specific conductivity was smallest in FMs, 100.3% of CK. While mulching treatment increased root activity in low temperature seasons, it decreased root activity in high temperature seasons. Change in root/shoot ratio was most significantly under plastic film mulching, with PMa and PMs values of 87.42% and 90.35% of that of CK, respectively. Within 0-20 cm soil layer and 40-60 cm horizontally around the plants, the largest proportion of fine roots was under PMa (reaching respectively 133.5% and 116.7% of CK) and the smallest proportion was under FMs. It suggested that mulching pattern was closely related with root growth and distribution. Also soil moisture changed soil environment and root distribution. Mulching was good for water and nutrient utilization in shallow soils and in horizontal far from Lycium barbarum.

Identification of chemicals in potato root exudates under different years of continuous cropping and their biologic effects

ZHANG Wenming, QIU Huizhen, ZHANG Chunhong, HAI Long

2018, 26(12): 1811-1818. doi: 10.13930/j.cnki.cjea.180086

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In order to explore possible obstruction mechanisms in continuous potato cropping systems, potato root exudates were collected in 1-5 years (CP₁-CP₅) continuous cropping systems of potato under field conditions. Chemical composition of root exudates was determined by the GC-MS method and biological effects of the exudates were detected by biological monitoring. The results showed that the main components of potato root exudates in CP₁-CP₅ treatments included organic acids, glucides, amines, alcohols, esters and pyrimidines, although the chemicals occurred in different quantities and contents. Palmitic acid occurred in all the CP₁-CP₅ systems, with relative contents of 0.55%, 0.87%, 1.24%, 1.05% and 0.95%, and concentrations of 7.12 mg·L^-1, 7.39 mg·L^-1, 9.46 mg·L^-1, 8.38 mg·L^-1 and 8.02 mg·L^-1, respectively. Biological analyses showed that potato root exudates significantly inhibited potato growth, with inhibition expression of CP₅ > CP₄ > CP₃ > CP₂ > CP₁. The inhibition of potato growth by palmitic acid had obvious concentration effects, with inhibition expression of 100 mg·L^-1 > 50 mg·L^-1 > 10 mg·L^-1 > 5 mg·L^-1. Potato root exudates obviously promoted the growth of Rhizoctonia solani. The colony diameter and mycelia fresh weight of R. solani were highest in CP₃ and lowest in CP₁. No significant differences were observed between CP₂, CP₄ and CP₅. Palmitic acid promoted the growth of R. solani. The colony diameter and mycelia fresh weight of R. solani increased firstly and then later decreased along with increasing concentration of palmitic acid. Colony diameter and mycelia fresh weight of R. solani were highest at 10 mg·L^-1. The study showed that potato root exudates significantly inhibited potato growth, and the inhibiting effect increased with increasing number of years of continuous cropping. The promotion of potato root exudates to R. solani growth exacerbated the obstacles of continuous cropping. Palmitic acid is the allelochemicals secreted by potato roots.

Evapotranspiration model and crop coefficient of greenhouse eggplant in North China

WANG Helei, LI Jiaxi, FAN Fengcui, HAN Xianzhong, LIU Shengyao, LI Zhihong, JIA Jianming, WANG Kejian, ZHANG Zhe, JIA Songnan

2018, 26(12): 1819-1827. doi: 10.13930/j.cnki.cjea.180192

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The theoretical basis of a model for estimation of evapotranspiration of greenhouse eggplants in North China was constructed for the development of optimized irrigation systems.Because irrigation of vegetables in North China has been much higher than crop evapotranspiration, severe deep soil water leakage has occurred, resulting in soil salinization and compaction.This has had a significant impact on the yield and quality of vegetables, resulting in larges waste of water resources.An evapotranspiration model was needed to not only guide irrigation to improve water use efficiency of vegetables, also lay the foundation for the application of agricultural information technology.It can be used to alleviate over-exploitation of groundwater and reduce frequent occurrences of diseases and pests in vegetables due to large amount irrigation.Therefore, it was necessary to establish a model that can accurately simulate vegetable evapotranspiration under greenhouse conditions.In this experiment, the effect of irrigation quota on yield and water use efficiency of eggplant in greenhouse was investigated by setting watering quotas of 15 mm (W1), 22.5 mm (W2), 30 mm (W3) and 37.5 mm (full irrigation quota, CK).The fields were irrigated to ensure sufficient water supply at seeding, flowering and maturity stages, at which the soil moisture contents were kept respectively at 70%, 80% and 70% of field capacity. Based on the modified Penman-Monteith equation and by analysis of relationship between crop coefficient and leaf area index of CK treatment, a model for the evapotranspiration based on meteorological data and leaf area index was established.The model was validated by measured evapotranspiration data under W1, W2 and W3.The results showed that average relative errors between the measured evapotranspiration for W1, W2 and W3 and the simulated values by the model were respectively 17.81%, 18.31% and 17.97%. This showed that the modified Penman-Monteith equation accurately estimated reference crop evapotranspiration under greenhouse conditions.Crop coefficient (K_c) had a significant linear regression with leaf area index (LAI), K_c=0.21 LAI+0.199 1(P < 0.05), indicating that it was possible to determine crop coefficient from leaf area index.The simulated results showed on significant difference in yield (P > 0.05), and significant difference in WUE (P < 0.05) between W2 and CK.WUE of W2 was 31.59% higher than that of CK, indicating that W2 addressed both yield and WUE.Crop coefficients of eggplants at seedling stage and flowering to fruiting period and ripening stage under W2 treatment were respectively 0.21-0.46, 0.62-0.94 and 0.70-0.92.The study suggested that the new model was applicable in estimating actual evapotranspiration of facility eggplants.It calculated crop coefficient that was of practical value in water-saving irrigation.The research was significant for guiding agricultural precision irrigation.

Physiological mechanism of FeSO₄ priming improvement of seed germination performances of Gentiana macrophylla

NIU Xiaoxue, MU Meng, LI Baohua, DONG Xuehui

2018, 26(12): 1828-1835. doi: 10.13930/j.cnki.cjea.180257

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Gentiana macrophylla is a widely used ingredient in traditional Chinese medicine for more than 2 000 years.Now, it is under third-class protection in China and on the list of National Key Protected Wild Herbs.G.macrophylla is a seed-propagated plant with extremely low germination rate.Short seed vigor, lower seed yield and after-ripening severely hinder its seedling establishment and significantly raise nursery cost.Various priming methods have shown that ferrous priming is better than other liquid priming, having higher germination performance under both optimal and adverse environments than non-primed seeds.The objectives of this study was to investigate the physiological mechanism of FeSO₄ priming increasing seed germination performance of G.macrophylla to lay the theoretical basis for FeSO₄ priming in abiotic stress response and application of FeSO₄ priming technology in other plants seeds.Compare with non-priming of seeds, we investigated the effects of 0.6% FeSO₄ priming on seed membrane permeability, stored material metabolism, energy metabolism, hormone homeostasis and enzyme activity.In this study, we noted that FeSO₄ reduced seed membrane permeability and improved seed vigor by decreasing electrical conductivity by 6.61% at 12 h, 11.67% at 24 h.The mobilization of stored materials such as sugars, proteins and fatty acids were activated, sucrose content decreased by 9.57%, and soluble protein content increased by 49.63%.With regard fatty acids, content of saturated fatty acids increased by 4.93% for myristic acid and 9.03% for methyl lignocerate.Then the content of unsaturated fatty acids decreased by 6.73% for behenic acid, 8.18% for oleic acid, 8.40% for linoleic acid and 6.70% for inolenic acid.In addition, FeSO₄ priming altered hormone homeostasis of seeds between ABA and GA, of which ABA content decreased by 64.78% and GA content increased by nearly 22 times.In terms of energy metabolism, FeSO₄ priming remarkably improved energy level, increased ATP content by 2.16 times and increased cytochrome C oxidase activity by 67.91%.Moreover, FeSO₄ priming acted as an initial stress-exposure, both enzyme-catabolized and non-enzyme-catabolized systems response to environmental stress were activated.This was specifically so for the activities of SOD, CAT, APX of enzyme-catabolized elements, which increased by 2.85 times, 1.79 times and 19.6%, respectively.The contents of non-enzyme-catabolized elements were increased by 74.08% for glutathione and 10.89% for ascorbic acid.In summary, our study indicated that regulation of FeSO₄ priming was a complex process that promoted stored material mobilization, ATP biosynthesis, key enzyme activation, phytohormone homeostasis between ABA and GA; and simultaneously regulated both enzymatic-catabolized and non-enzymatic-catabolized effecters in biotic and an-biotic stress.On the one hand, priming induced more advanced development in seeds towards complete germination than unprimed ones.On the other hand, priming was considered as a pre-germination stress-exposure that left seeds with "stress-memory" and improved anti-adversity ability.These changes were not eliminated even when seeds dried to original moisture content.This was the main reason why priming enhanced seed vigor and rapid, uniform seed germination performance.

A method for evaluating climate quality of Dangshansu pear using key quality factors

LI De, GAO Chao, SUN Yi, YANG Jian, FAN Xiaoling

2018, 26(12): 1836-1845. doi: 10.13930/j.cnki.cjea.180378

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Establishing methods for the evaluation of effects of climate on quality of pear fruit is the technical basis for assessing climate quality of fruits. This study used selected quality factors of Dangshansu pea for in situ monitoring and contemporaneous meteorological data in Dangshansu pear planting area for the period 1996-2015, and clarified the key quality factors of Dangshansu pear and the driving meteorological factors. Based on relevant research and expert knowledge, the correlation analyses, empirical functions and stepwise functions, ranked analyses, stepwise regressions, probability quantiles and weighted sums were used to establish the evaluating method of climatic effect on Dangshansu pear quality. The quality of Dangshansu pear was assessed by using the established method. The results showed that the ten key quality factors that reflected the climate quality of Dangshansu pear were fruit surface integrity, fruit surface rust, fruit shape index, maximum single fruit weight, average fruit weight, first-fruit rate, substandard fruit rate, fruit crispness, fruit sugar content and fruit stone cell degree. The 28 key meteorological factors determined the quality of Dangshansu pear. The climate quality of Dangshansu pear was characterized by composite index of climate quality which was the weighted sum of apparent climate quality index and intrinsic climate quality index. Climate quality was divided into four levels:extra excellent, excellent, good and general. The corresponding thresholds of comprehensive index of climate quality were ≥ 3.5, 2.5-3.5, 1.5-2.5 and < 1.5. The weights of apparent climate quality index and intrinsic climate quality index were 0.70 and 0.30, respectively. The weights of fruit surface integrity, fruit surface rust, fruit shape index, maximum single fruit weight, average fruit weight, first-fruit rate and substandard fruit rate that constituted the apparent quality index of climate quality index were 0.376 1, 0.232 8, 0.108 8, 0.074 9, 0.088 6, 0.088 7 and 0.029 9, respectively. The weights of crunchiness, sugar content and stone cell degree of fruits that comprised intrinsic climatic quality index were 0.637 6, 0.104 6 and 0.257 8, respectively. Each quality factor was described by a quantitative model constructed with corresponding key meteorological factors. The comprehensive index of climate quality of Dangshansu pear picked in late September in Dangshan County in 2016 was 2.58 — which was judged as "excellent" and consistent with actual conditions. The evaluation model established in this study was practicable for evaluating climate quality of Dangshansu pear.

Biochar effect on soil physical properties: A review

DONG Xinliang, LIN Qimei

2018, 26(12): 1846-1854. doi: 10.13930/j.cnki.cjea.180277

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Biochar is charred biomass produced under limited or no oxygen (O₂) supply and at high temperature. Rich in aromatic carbon (C), biochar can persist in soil for hundreds or thousands years. Biochar application in agricultural soils has attracted an intensive global research with extensive reviews of biochar characteristics, effects on soil chemical, biological and physical properties and on crop growth. However, the work on the effect of biochar on soil physical properties is not as detailed as those on soil chemical and biological properties. In this study, relevant publications on the effect of biochar on soil physical properties in recent decades were searched and summarized. The results indicated that biochar application reduced soil bulk density, improved soil aggregate stability, field water holding capacity, soil available water content, and decreased saturated hydraulic conductivity through direct and indirect ways. Biochar has huge specific surface area and porosity, which directly influences soil physical properties such as reducing soil bulk density and increasing water holding capacity and soil available water content. Furthermore, biochar particles combine with soil minerals to change soil structure and create the proper environment for soil microbial and plant root growth, which ultimately affect soil physical properties. Indirectly, the effect of biochar on soil physical properties includes improved soil aggregate stability and saturated hydraulic conductivity. The effect of biochar on soil physical properties is related to biochar application rate, feedstock type, pyrolysis temperature, particle size, soil texture and duration in the soil. Generally, the higher the amount of biochar applied, the more significant are the induced changes in soil physical properties (bulk density, water holding capacity and saturated hydraulic conductivity). Woody biochar significantly increases saturated hydraulic conductivity, while grass biochar has no effect on saturated hydraulic conductivity. In addition, as the duration after biochar application increases, its effect on soil physical properties decreases. However, very limited studies have investigated this relationship under long-term filed conditions, and field experiments have been even relatively scarce. Consequently, the further studies should focus on the long-term effects of biochar application on soil physical properties in filed condition, and investigate the mechanisms behind the biochar effect on soil physical properties, which is essential to provide scientific evidence for the real agricultural production and ecological improvement. Furthermore, the relationships between biochar characteristics and soil physical properties are not fully known. Thus, there are needs to further investigate the effect of biochar application on the interaction of soil physical and chemical, biological properties and the mechanisms.

Characteristics of soil fertility quality and minimum dataset for yellow-mud paddy fields in Fujian Province

WANG Fei, LI Qinghua, LIN Cheng, HE Chunmei

2018, 26(12): 1855-1865. doi: 10.13930/j.cnki.cjea.180194

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In modern agricultural production, the quality of soil fertility is crucial for the crop productivity.Yellow-mud paddy fields constitute one of the main types of medium-to-low yield fields in Fujian Province, which accounts for about 30% of paddy fields in the province.In order to determine key limiting factors, evaluate the quality of soil fertility and implement targeted improvement measures, 28 soil characteristics of 20 pairs of typical surface soil samples from yellow-mud paddy fields and high-yield grey-mud fields in the neighboring and the same landscape units in Fujian Province were compared.Differences in soil properties between the two soils and the causes were systematically analyzed and the minimum data set (MDS) for assessment of the quality of soil fertility in yellow-mud paddy fields established using principal component analysis and other methods.Using the weighted index method, the soil fertility quality index (SFQI) from MDS and the important data set (IDS) constituted on the basis of significantly different factors. The results showed that compared with grey-mud paddy fields, the content of organic matter in yellow-mud paddy fields was less by 19.1% and the contents of total nitrogen, total phosphorus and total potassium were less respectively by 14.8%, 29.9% and 25.4%. Also the contents of available nitrogen, available phosphorus and available potassium were less respectively by 17.8%, 56.7% and 39.3%.CEC and the contents of exchangeable calcium, exchangeable magnesium were less respectively by 12.9%, 50.6% and 30.8%. While the contents of available iron, available boron and available zinc were less respectively by 25.6%, 33.3% and 44.1%, the contents of clay < 0.001 mm and bulk density were higher by 20.8%, 25.6% and 12.3%, whereas the porosity was less by 19.3%. Compared with grey-mud paddy fields, the activity of catalase in yellow-mud paddy fields was higher by 20.4%, but the activity of urease was less by 40.4%.This indicated that compared with high-producing fields, yellow-mud paddy fields belonged to low-fertility and short-acting soils with insufficient soil organic matter, total nutrients and available nutrients, low contents of macro/micro elements, CEC, etc.The above 19 soil characteristics with significant differences between the two soils constituted the IDS.Six principal components, with cumulative contribution of 76.22%, were selected from IDS reflecting the synthetic fertility properties of yellow-mud paddy fields.The final established MDS composed of five factors, including CEC, total potassium, available phosphorus, available boron and porosity for fertility quality assessment according to the expert experience and correlation analysis.The calculated SFQI from MDS of yellow-mud paddy fields was equivalent to 69.5% of that of grey-mud paddy fields. Correlation analysis on SFQI for IDS and MDS indicated that MDS could replace IDS and correctly used to evaluate soil fertility quality of yellow-mud paddy fields.Moreover, MDS could also be used in studies on how to improve soil fertility.

Effect of fertilization managements on soil organic carbon and microbial community structure

LI Qian, MA Kun, YE Xiuxiang, YANG Jinjuan, NIU Hongxia, MA Ling

2018, 26(12): 1866-1875. doi: 10.13930/j.cnki.cjea.171190

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Abstract:
The Phospholipid Fatty Acids (PLFAs) fingerprint and humus fraction methods were used to determine the accumulation of soil organic carbon in cultivated farmlands and the interaction mechanisms of soil microbial communities with soil organic carbon. The combined effects of organic manure and chemical fertilizer on soil organic carbon accumulation, soil humus forms and their relationships with soil microbial community structures were studied in a 5-crop rotation mode of 'potato-potato-oil sunflower-potato-oil sunflower' over a period of five years. The experimental treatments were as follows-no fertilization, inorganic fertilizer application, combined application of inorganic fertilizer and cow dung, combined application of inorganic fertilizer and sheep manure, combined application of inorganic fertilizer and biological organic fertilizer, and then combined application of inorganic fertilizer and fulvic acid potassium. The results showed that soil organic carbon fluctuated with increasing tendency over the five-year period. Compared with the control (no fertilization), soil organic carbon increased at annual average rates of 6.61% and 8.97% under the treatments of combined application chemical fertilizer with cow dung or separately with sheep manure. The rate of accumulation of soil organic carbon was influenced by the amount and type of added exogenous organic matter to the soil. The contents of stable or tightly combined humus and ratio of loosely combined humus to tightly combined humus increased following the addition of high quantities of organic manure (chemical fertilizer plus cow dung or chemical fertilizer plus sheep manure) and inorganic fertilizer. Compared with no fertilization, there were significant differences in soil bacteria, fungi, actinomycetes, protozoa and total microbial biomass, marked by phospholipid fatty acids under combined application of inorganic fertilizer and sheep manure or cow dung. The biomass ratio of gram-positive bacteria to gram-negative bacteria (G⁺/G^-) in the treatments with inorganic fertilizer plus organic fertilizers decreased. There was no obviously difference in the ratio of G⁺/G^- among treatments of combined application of inorganic fertilizer and organic fertilizers. Multivariate analysis showed a good correlation between the first ordination axes based on soil microbial biomass marked by PLFAs and the second ordination based on combined soil organic carbon and humus (P₁=0.568, P₂=0.611). The relationship between soil microbial biomass and soil environmental factors was explained by the 98.69% cumulative variation in spatial scale. There was a positive correlation between the content of loosely combined humus and G⁺/G^- of soil microbial community. It was concluded that the tightly combined humus fraction gained higher stability than the loosely combined humus when exogenous organic carbon was applied to the soil. The soil bacteria and fungi biomass marked by PLFAs were promoted with increasing amounts of exogenous organic carbon in the soil. The biomass ratio of fungi to bacteria was not influenced by fertilizer management and amount of exogenous organic carbon. Generally, the change in soil microbial community structure was driven by the change in soil organic carbon content and soil humus fraction. Combined inorganic fertilizer with cow manure and inorganic fertilizer with sheep manure supported the accumulation of soil organic carbon and the formation of loose combined humus, but also promoted an increase in soil microbial biomass. The research provided a reliable scientific basis for soil fertilization in semiarid areas in Ningxia.

Effect of long-term fertilization on soil phosphorus characteristics and loss risk of red soil

XIA Wenjian, JI Jianhua, LIU Jia, LI Zuzhang, YU Xichu, WANG Ping, LI Daming, LIU Xiumei, WANG Shaoxian, LI Yao

2018, 26(12): 1876-1886. doi: 10.13930/j.cnki.cjea.180532

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Abstract:
In order to determine the effects of long-term fertilization on soil phosphorus loss risk in red soil, a study on soil phosphorus adsorption and retention and the related driving factors in red soils was conducted. A long-term fertilization experiment was started in 1986 under double corn cropping system in Jingxian County, Jiangxi Province. The treatments included no-fertilizer control (CK), sole chemical nitrogen fertilizer (N), sole chemical phosphorus fertilizer (P), sole chemical potassium fertilizer (K), chemical N, P and K fertilizers (NPK₁), double doses of chemical N, P and K fertilizers (NPK₂), sole organic manure (OM), and organic manure plus chemical N, P and K fertilizers (MNPK). Soil total phosphorus (TP), available phosphorus (Olsen-P), double acid-extractable phosphorus (Mehlich 1-P), water-soluble phosphorus (CaCl₂-P), phosphate sorption index (PSI), and phosphorus saturation degree (DPS) were measured. Isothermal adsorption and desorption characteristics of soil phosphorus were determined and the relationship between soil phosphorus parameters and soil organic carbon, pH and CEC analyzed using simple and canonical correlation analyses. The results showed that long-term application of chemical phosphorus fertilizer supplemented soil phosphorus (especially TP) and increased Olsen-P and Mehlich 1-P, but had no significant effect on CaCl₂-P. The effect of chemical fertilizer application on DPS was not significant. Phosphorus fertilizer reduced PSI, NPK₁ treatment increased PSI, but NPK₂ had no significant difference with CK. Under long-term application of organic manure (pig manure, OM and MNPK), soil TP and DPS increased, then Olsen-P, Mehlich 1-P and CaCl₂-P accumulated significantly, but PSI decreased. Results from soil P sorption isotherms simulated using the Langmuir equation produced a coefficient in the range of 0.862-0.989. CK and chemical fertilizer treatments had high maximal phosphorus adsorption (Q_m) and phosphorus adsorption affinity constant (k), while under long-term organic manure application (OM and MNPK treatments) Q_m and k reduced. The isotherms for phosphorus desorption showed that CK and chemical fertilizer treatments increased phosphorus desorption rate with increasing phosphorus concentration. Organic fertilizer treatments (OM and MNPK) had high phosphorus desorption rate under low phosphorus concentration, but low phosphorus desorption rate under high phosphorus concentration. Under long-term application of chemical fertilizers, soils phosphorus adsorption and fixation increased with new additions of phosphorus, but organic fertilizers reduced phosphorus adsorption in the soil. Soil TP, Olsen-P, Mehlich 1-P, CaCl₂-P, PSI, DPS and Q_m had significant correlation with pH, CEC, soil total organic carbon (TSOC), cold water soluble organic carbon (CWSOC) and hot water soluble organic carbon (HWSOC). There was a canonical correlation between soil phosphorus indexes and soil organic carbon, pH and CEC, with significantly canonical correlation coefficients of 0.997 and 0.951 for the first and second pairs of typical variables. The correlation coefficient between water soluble organic carbon (HWSOC and CWSOC) and the first pair of typical variables (U₁ and V₁) was highest, followed by soil pH. The study showed that the application of organic fertilizer positively affected soil phosphorus supply and retention. Soil water soluble organic carbon and pH were key indexs of phosphorus supply and risk of phosphorus loss in red soils.

GIS-based pollution risk assessment of nitrogen and phosphorus loss in surface runoff in farmlands in Fujian Province

KANG Zhiming, ZHANG Rongxia, YE Yuzhen, WU Renye, WANG Songliang

2018, 26(12): 1887-1897. doi: 10.13930/j.cnki.cjea.180118

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Abstract:
Nitrogen and phosphorus loss in surface runoff from farmlands has been the main cause of water eutrophication.Fujian Province is one of the regions with the highest intensity of fertilizer application per unit area of land in China.The subtropical monsoon climate zone and hilly region with heavy summer and autumn rains on steep hill-slope farmlands in Fujian increase the risk potential for pollution.Thus to analyze current conditions and characteristics of nitrogen and phosphorus loss in surface runoff from farmland in Fujian Province, we selected nine prefectural level cities in Fujian Province as the study areas to estimate the loss of nitrogen and phosphorus in surface runoff in farmlands based on investigated data of fertilizer use in the cities for the period from 1985 to 2016.By integrating the three factors of pollution risk (fertilizer loss, rainfall and drainage intensity), we evaluated nitrogen and phosphorus pollution risk from farmland fertilizer to determine critical areas of primary concern.We used the ArcGIS platform to make thematic maps for visualizing the spatial distribution of contaminated areas by nitrogen and phosphorus.The results showed that fertilizer application in Fujian Province increased during the 30-year period from 4.911×10⁵ t to 1.239×10⁶ t, with an annual average rate of increase of 3.03%.The amount of fertilizer use in Fujian Province was highest (1.243×10⁶ t) in 1999, accounting for 3.01% of total fertilizer use in China.The intensities of nitrogenous and phosphate fertilizer use in Zhangzhou City were largest, with respective values of 880.40 kg·hm^-2 and 429.21 kg·hm^-2.The high nitrogen and phosphorus surface runoff were concentrated in Zhangzhou City, which were respectively 1.571×10⁶ t and 3.590×10⁵ t, with nitrogen and phosphorus loss intensities of 8.71 kg·hm^-2 and 1.99 kg·hm^-2.However, pollution risk values of nitrogen and phosphate fertilizer were highest in Nanping City, reaching respectively 63.19% and 63.37%-a high risk of nitrogen and phosphorus pollution.Xiamen City had the lowest risk values, respectively 0.53% and 0.53%.The others were in between and in the following decreasing order:Ningde City (57.22% and 54.48%) > Sanming City (53.34% and 53.34%) > Longyan City (51.38% and 51.20%) > Zhangzhou City (46.73% and 46.73%) > Quanzhou City (45.49% and 40.25%) > Fuzhou City (34.35% and 33.80%) > Putian City (18.59% and 16.93%).By using cluster analysis, these nine cities were divided into three groups-heavy to moderate pollution risk (Sanming City, Longyan City, Ningde City and Nanping City), moderate to light pollution risk (Quanzhou City, Zhangzhou City and Fuzhou City) and low pollution risk (Xiamen City and Putian City).We concluded that Zhangzhou City needed to emphasize on reducing nitrogen and phosphorus fertilizer use in agriculture.Nanping City needed to hammer at risk control of nitrogen and phosphorus loss in farmlands.The others cities needed to strengthen the development of ecological agriculture to facilitate the construction of Fujian Experimented Region of Ecological Civilization and the promotion and optimization of control measures of nitrogen and phosphorus loss in surface runoff.

Livestock manure emission and cultivated land pollution load in the midst upstream of Danjiang River in Shangluo City

WANG Mangsheng, ZHANG Shuangqi, YANG Jiyuan, YANG Lei

2018, 26(12): 1898-1907. doi: 10.13930/j.cnki.cjea.180174

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Abstract:
Persistent water quality safety and protection have been a hot research in the upstream region of the middle route of China's South-to-North Water Diversion Project. Shangzhou District, Danfeng County and Shangnan County, which are governed by Shangluo City, have already delineated the zone for water source protection in the upstream reach of Danjiang River. There is a need of basic research on scientific management of livestock and efficient implementation of research on water source protection area. It is also necessary to understand development status of livestock, estimate livestock manure emission, analyze absorption capacity of cultivated lands, and evaluate pollution risk caused by the emission. Until now, less data or literature has existed on this field of research. In this study, the emission of livestock manure was estimated using the livestock manure emission coefficient method from 2014 to 2016 in the upstream region of Danjiang River in Shangluo City, including Shangzhou District, Danfeng County and Shangnan County along the river direction. Then the maximum cultivated land load of pig-waste equivalent was confirmed according to cultivated area and pollution risk of cultivated land due to livestock manure in the three districts was evaluated. The results showed that annual pig-waste equivalents of livestock manure in Shangzhou, Danfeng and Shangnan were respectively 5.732×10⁵ t·a^-1, 9.321×10⁵ t·a^-1 and 1.274×10⁶ t·a^-1, with livestock manure emissions from pig and poultry accounting for up to 68.06% of the total. The cultivated land load of pig-waste equivalents for livestock manure were respectively 27.04 t·hm^-2·a^-1, 76.72 t·hm^-2·a^-1 and 90.10 t·hm^-2·a^-1 in Shangzhou, Danfeng and Shangnan. The maximum standard of cultivated land load of pig-waste equivalent of livestock manure was 61.22 t·hm^-2·a^-1 for Shangluo City. Pollution risks were level Ⅱ for Shangzhou (moderate risk), and level Ⅳ for both Danfeng and Shangnan (severe risk). The average cultivated land loads for total nitrogen were respectively 159 kg·hm^-2·a^-1, 450 kg·hm^-2·a^-1 and 530 kg·hm^-2·a^-1 in the three districts; for total phosphorus were 51 kg·hm^-2·a^-1, 179 kg·hm^-2·a^-1 and 199 kg·hm^-2·a^-1; for biochemical oxygen demand (BOD) were 716 kg·hm^-2·a^-1, 2 275 kg·hm^-2·a^-1 and 2 595 kg·hm^-2·a^-1; for chemical oxygen demand (COD) were 768 kg·hm^-2·a^-1, 2 345 kg·hm^-2·a^-1 and 2 667 kg·hm^-2·a^-1; and for NH₃-N were 65 kg·hm^-2·a^-1, 201 kg·hm^-2·a^-1 and 232 kg·hm^-2·a^-1. It was concluded that the number of livestock bred was large and the husbandry structure unreasonable in the three districts of Shangluo City. Because of the limited cultivated land, cultivated land loads and livestock manure pollution were pretty heavy, with increasing risks from upstream to downstream reaches. Excessive pollutants caused loss of nitrogen and phosphorus, which severely threatened water source safety of the South-to-North Water Diversion Project.

Change in rocky desertification and effect of socio-economic activities in Guizhou

WANG Xiaofan, XU Erqi, ZHANG Hongqi, ZHANG Quanjing

2018, 26(12): 1908-1918. doi: 10.13930/j.cnki.cjea.180459

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Abstract:
Rocky desertification is one of the most severe ecological problems in China. It has accelerated environmental degradation, caused frequent soil erosion and natural disasters, threatened people's living environment and restricted social and economic development. Analysis of the factors driving rocky desertification can be used to determine the factor that control rocky desertification and support strategies to combat the desertification. Studies have mainly focused on the geological background, geomorphological characteristics, meteorological factors, ecological restoration and governance projects. However, these studies have fallen quantification of the related social and economic activities. Thus there is the lack of a deep insight into the impact of the changes in regional rocky desertification and socio-economic activities. Using Guizhou Province as a case study area, this paper used GIS, remote sensing and statistical techniques (including Arcgis, Recognition Development and SPSS) to analyze the relationship between those neglected variables at county scale. Based on the 2000 and 2011 karst-rock desertification distribution maps, dynamic changes in rocky desertification in Guizhou Province in 2000-2011 were analyzed. The impact of social economic activities on rock desertification in karst area of the province was analyzed to lay theoretical basis for subsequent works on rocky desertification. The main conclusions of the study were as follows:1) one quarter of the karst area in Guizhou Province was still affected by rocky desertification in 2011, the control of which was still an arduous task. Based on spatial distribution, rocky desertification in Guizhou Province was relatively severe in the west and south of the study area and relatively mild in the east and north. The area of rocky karst desertification in Guizhou Province was on the whole improving. Different classes of rocky desertification were violently transformed into the other. Mild karst rocky desertification occurred in most of the area where there was improvement in rocky desertification, but the task of restoring light, moderate, severe and extremely severe rocky karst desertification was still very arduous. It also suggested that not only was attention needed to restore light, moderate, severe and extremely severe rocky karst desertification, but also to protect against potential areas of no rocky karst desertification. 2) The correlation analysis to determine the factors driving rocky desertification showed that multiple factors (including population factors, socio-economic development, agricultural production activities, terrain slope and ecological engineering construction) were critical in the evolution of rocky desertification in the region. Agricultural activities had the most significant effect on rocky desertification, including the proportion of agricultural population, total agricultural output, cultivated land area per cap., cultivated land proportion in 15°-25° slope, cultivated land proportion at > 25° slope, karst proportion at 15°-25° slope, karst proportion at > 25° slope. The correlation coefficients for these factors with rocky desertification were 0.473, 0.425, 0.291, 0.288, 0.430, 0.338 and 0.334, respectively. The study of the impact of socio-economic activities on rocky desertification provided the required expertise on the control of rocky desertification in the region.

Emergy analysis of chicken breeding modes under low-efficient Pinus massoniana forests

GAO Chengfang, HUANG Ying, ZHANG Xiaopei, LUO Xuhui, CHEN En, LI Wenyang, WENG Boqi

2018, 26(12): 1919-1928. doi: 10.13930/j.cnki.cjea.180301

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Abstract:
Pinus massoniana forest is a typical low-efficient vegetation type in eroded red-soil areas. Ecological breeding of chicken under forest is a new mode that includes traditional raising chicken under forest and grass planting underneath. This model can reduce soil erosion in P. massoniana forests and improve economic performance. To evaluate ecological and economic benefits of ecological breeding of chicken under P. massoniana forest, this paper used emergy analysis method to evaluate self-sufficiency, investment value, net emergy output, environmental load rate, sustainable development index and emergy feedback rate of traditional chicken breeding mode (CK) and ecological chicken breeding mode (ECB) under P. massoniana forests in Tongba Village, Sanzhou Town and Changting County. The results showed that self-sufficiency, investment value, net emergy output, environmental load rate, sustainable development index, and emergy feedback rate of CK were respectively 0.860, 0.166, 2.125, 3.380, 0.629 and 0.026. Then those of ECB were respectively 0.400, 1.510, 0.870, 1.370, 0.635 and 0.290. The values of investment and sustainable development indexes of ECB increased respectively by 1.344 and 0.006 over those of CK, showing stronger economic vitality. The self-sufficiency and environmental load rate of ECB reduced respectively by 0.460 and 2.010 compared with CK, showing lower environment stress. Net emergy output was lower by 1.255 units and emergy feedback rate higher by 0.264 units over CK. Input-output ratio of CK was 0.30, and that of ECB was 0.53, resulting in high emergy self-sufficiency. Net energy output rate and environmental load of ECB were lower than those under CK, while emergy investment rate and sustainable development index were higher. In general, ecological chicken breeding under forest had stronger economic vitality and lower environment stress, and consequently, was consistent with the trend of economic development in vulnerable forest areas. Poor soil structure in soil erosion areas limited the functions of chemical fertilizer in the circulatory system. This led to low net emergy output and emergy feedback rate. This result was indicative for the optimization of forestry economy modes.

2018 Vol. 26, No. 12