Over-irrigation and fertilization as well as the resulting low water use efficiency (WUE) and fertilizer use efficiency (FUE) have become major constraints on global crop production. A 2-year field experiment explored the effects of a soil conditioner combined with different irrigation and fertilization regimes on potato performance. The design included two sets of treatments varying irrigation frequency (6-, 8-, 10-day intervals) with either reduced fertilization (70–100

Over-irrigation and over-fertilization waste a lot of water and fertilizer nutrients, increasing cost and environmental pollution in semi-arid areas. Soil conditioner has multiple beneficial effects in agricultural production, but the effects of soil conditioner addition combined with water and fertilizer reduction on crop growth and yield are still unclear. In this study, the effects and mechanisms of conventional irrigation (6.23 x 10(3) m(3)/ha) and fertilization (N: 225 kg/ha; P2O5: 350 kg/ha; K2O: 400 kg/ha) (CK), 30 % water reduction combined with conditioner addition (RI), 30 % fertilizer reduction combined with conditioner addition (RF), and 30 % water reduction combined with 30 % fertilizer reduction and conditioner addition (RIF) on the soil nutrient transformation and potato yield were explored from the perspectives of soil microbial community and metabolome. The results showed that RI, RF, and RIF treatments all reduced soil total organic carbon (TOC) content, increased soil NO3--N content, and changed the composition of soil bacterial community and rhizosphere soil metabolites. Specifically, RI and RIF treatments significantly reduced the Shannon index and Chao1 index of soil bacterial community and the quantity of metabolite types in rhizosphere soil. However, RF treatment increased the quantity of metabolite types in rhizosphere soil, especially the metabolites involved in the Alpha-Linolenic acid metabolism, Starch and sucrose metabolism and Biotin metabolism pathways. In addition, RI and RF treatments increased the phosphorus accumulation in plants while maintaining the yield compared with CK. The redundancy analysis and Mantel test found that soil TOC and NO3--N content significantly affected soil differential bacterial genera, and the differential bacterial genera and differential abundant metabolites (DAMs) in rhizosphere regulated potato yield by affecting plant nutrient uptake and dry matter yield. The structural equation model and path effect analysis found that plant nutrient uptake was the main factor influencing potato yield. Soil NO3--N content and differential bacterial genera directly affected plant nutrient uptake, and soil TOC and starch and sucrose metabolism indirectly affected plant nutrient uptake. This study will provide a technical reference for increasing potato yield, reducing potato planting costs, and achieving sustainable agricultural development.

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The application of soil conditioner has become one of the most important strategies to reduce nitrogen (N) losses from agricultural fields. However, it is still unclear about the effect of conditioners on soil profile N accumulation and crop N utilization under different irrigation levels. In this study, the effects of combination of N fertilizer (255 kg/ha) and different doses of soil conditioner (mixture of anionic polyacrylamide, polyvinyl alcohol, and manganese sulfate) (0 (N), 0.008 (P1N), 0.016 (P2N), and 0.024 (P3N) g/kg) on soil - oat crop N transport and oat crop N utilization were explored under different irrigation levels (conventional irrigation volume (4.1 × 106 L/ha), W100; 80

Polymer materials positively affect the physical, chemical, and microbiological properties of soil. However, little is known about the response mechanism of soil carbon and nitrogen transformation to polymer materials. This study explored the effects of three polymer materials (humic acid extracted from cottonseed meal, H; modified polymer prepared by using polyacrylamide as main raw material, P; and composite polymer material composed of humic acid and modified polymer, HP) on the soil physicochemical properties, organic carbon (TOC), total nitrogen (TN), carbon and nitrogen fractions, and bacterial community structure in planted and non-planted soils under drip irrigation. The results showed that the application of H and P reduced soil bulk density (BD), improved soil aggregate stability (including soil aggregates > 0.25 mm, R0.25; mean weight diameter, MWD; and mean geometric diameter, GWD), and increased the content of TOC, TN, and carbon and nitrogen fractions (including labile organic carbon content, LOC; soil carbon management index, CMI; NO3−-N; NH4+-N; microbial biomass carbon, MBC; microbial biomass nitrogen, MBN). Polymer materials all could increase the diversity of bacterial communities, especially H (the diversity of bacterial communities in H treatment was 1.8% and 2.4% higher than that in the CK in planted and non-planted soil, respectively (p < 0.05)). The application of H and P reduced soil BD, and improved soil R0.25, MWD, GWD, TOC, TN, LOC, CMI, NO3−-N, NH4+-N, MBC, and MBN. Redundancy analysis (RDA) showed that the application of H and P improved soil TOC, TN, and carbon and nitrogen fractions by increasing the water stability of soil aggregate, and the increase of soil MBN indirectly improved the bacterial community structure.

Polymer materials have the effect of retaining water and increasing yield in irrigated agricultural systems. However, little is known about how polymer materials affect soil properties. The purpose of this study was to evaluate the effect of humic acid (H) (an alkaline extract of cottonseed meal), modified polymer (P) (a mixture of anionic polyacrylamide, polyvinyl alcohol, and manganese sulfate), and composite polymer (HP) (1:1 mixture of H and P) on soil physicochemical properties and structural diversity of bacterial community in soils with/without plants under drip irrigation. The results demonstrated that the application of polymer materials decreased soil bulk density, and increased soil moisture content. Compared with the control in soil with plants (CK), the H and P treatments decreased soil bulk density (BD) by 0.09 g.cm(-3) and 0.08 g.cm(-3), respectively (p < .05) after 90 days of culture. Meanwhile, the H, P, and HP treatments increased soil moisture content (MC) by 10.6%, 33.9%, and 16.5%, respectively (p < .05). For soil without plants, the P-NP treatment decreased BD by 0.18 g.cm(-3) (p < .05) after 90 days of culture. Although there were differences in soil pH and conductivity (EC) between treatments, they were not significant. As the culture time was prolonged, the relative abundance of soil Latescibacteria in soil without plants significantly increased compared with that in soil with plants. Principal component analysis (PCA) showed that the effects of polymer material application on soil microbes were not significantly different at the early stage of culture. However, there was significant (in soil with plants, r = 0.540, p = .004) or extremely significant difference (in soil without plants, r = 0.333, p = .045) between treatments after 90 days of culture. Among them, the difference between P treatment and CK was the most significant. Further analysis showed that the P treatment increased relative abundances of soil Acidobacteria, Gemmatimonadetes, and Nitrospirae by 20.6%, 42.8%, and 31.1% compared with CK, respectively (p < .05); and the P-NP treatment increased relative abundances of Gemmatimonadetes, Chloroflexi, and Latescibacteria by 60.5%, 35.7%, and 29.3% (p < .05) compared with CK-NP, respectively. The redundant analysis (RDA) showed that the application of polymer materials could improve the structure diversity of soil bacterial communities by increasing soil MC and regulating C/N ratio, regardless of soil with/without plants.

Nitrogen management is the key to improve crop yield. Polymer materials are widely used as water‐retaining agents in agriculture, but little is known about how polymer materials affect the transformation and utilization of soil nitrogen. This study focused on the effects of three polymer materials (humic acid extracted from cottonseed meal, H; modified polymer prepared by using polyacrylamide as main raw material, P; and composite polymer material composed of humic acid and modified polymer, HP) on the characteristics of soil and plant nitrogen accumulation in soils with/without plants under drip irrigation. The results showed that polymer materials increased the nitrogen accumulation and dry weight of leaf, spike axis + husk and grain, but decreased those of stem. Among them, the H treatment had the highest nitrogen uptake (34.5 kg·hm−2) after flowering stage, and the P treatment had the highest nitrogen transport (21.1% higher than no polymer materials, CK). Moreover, the wheat yields for the H and P treatments significantly increased by 19.7% and 12.6%, respectively. Polymer materials had an inhibitory effect on nitrogen fractions (soil total nitrogen (TN) and microbial biomass nitrogen (MBN) at the early stage of the culture, but there were significant improvements at the flowering and mature stages. The effects of polymer materials on the storage of TN and its fractions were different. Among them, the storages of soil TN, nitrate‐nitrogen (SNO3‐‐N), and ammonium‐nitrogen (SNH4+‐N) for the H treatment were increased, but the SNO3‐‐N in soil with plants was decreased by 1,317 kg·hm−2 compared with that in soil without plants, and the decrease was the largest among the decreases caused by the three polymer materials; the soil SNO3‐‐N for the P treatment was increased, but also the decrease in the SNO3‐‐N was smaller than that for the H treatment; the SNO3‐‐N for the HP treatment was increased, but the SNH4+‐N was decreased. Redundancy analysis showed that humic acid and modified polymer materials mainly increased soil MBN, NH4+‐N, and nitrogen accumulation of plant organs except for stem, which finally increases wheat yield.

The shortage of water resources promotes the development of water saving irrigation in arid land. Regulated deficit irrigation (RDI), as one of the water-saving irrigation technologies through applying a certain amount of water stress to the crops to promote the distribution of the photosynthate of crops to the needs of the tissues and organs, can save water and may increase yield. Our study evaluated the effect of the RDI on the sugar beet (Beta vulgaris L. cv. Beta356). Seven irrigation treatments were applied based on the growth stages of sugar beet (canopy development, storage root development, and sugar accumulation) and water deficit levels (30, 50, and 70% of field capacity [FC]). The yield, quality, sugar yield, irrigation water use efficiency (IWUE), and agronomic physiological traits of sugar beet were evaluated. Moderate water deficit (50% of FC) during canopy development increased sugar yield by 27% compared with the control (70% of FC during the whole growth stages). Severe (30% of FC) water deficit increased sugar yield by 45% during storage root development, and by 55% during sugar accumulation. The RDI during canopy development and storage root development inhibited leaf growth but did not affect yield. Malondialdehyde content and relative conductivity increased significantly when soil water content dropped to the irrigation threshold levels (i.e., 30% and 50% of FC) before rehydration during canopy development. After rehydration, there were significant increases in peroxidase activity and proline content (indicators of antioxidant defense and osmotic stress). Our results indicated that RDI increased yield at 30% and 50% of FC during three growth stages (canopy development, storage root development, and sugar accumulation) of sugar beet, which reduced irrigation water requirements. RDI could be applied as a strategic action for crop sustainability and water saving in arid land.

Polymer materials have broad potential applications for saving water and increasing crop yields in irrigated agricultural systems. However, little is known about how polymers affect the distribution and transformation of soil organic carbon. The purpose of this study is to evaluate the effects of humic acid (H) (an alkali extract of cottonseed meal), modified polymer (P) (a mixture of anionic polyacrylamide, polyvinyl alcohol, and manganese sulfate), and composite polymer (HP) (a 1:1 mixture of H and P) applied with drip irrigation on soil aggregate stability and organic carbon stability. The results demonstrated that the H and P treatments significantly increased soil aggregate stability and organic carbon content, compared with the HP treatment. Compared with the controls for corpped soils (CK) and uncorpped soils (CK-NP), the DR0.25 (>0.25 mm soil mechanical-stable aggregate), W-MWD (mean weight diameter of water stable aggregate), and W-GMD (geometric mean diameter of water stable aggregate) of the H treatment increased by 3.9%, 33.1%, and 23.2%, respectively (p < 0.05); the WR0.25 (>0.25 mm soil water stable aggregate), W-MWD, and W-GMD of the H-NP treatment (H treatment for uncorpped soils) increased by 44.7%, 38.0%, and 37.6%, respectively (p < 0.05); the WR0.25 and W-GMD of the P treatment increased by 29.8% and 26.8%, respectively (p < 0.05); and the W-GMD of the P-NP treatment (P treatment for uncorpped soils) increased by 16.5% (p < 0.05). Although the HP treatment also increased the organic carbon content of soil aggregates, it was less effective for improving soil aggregate stability. During the first 20 days of incubation, the mineralisation rate of the CK was the highest. Then, the mineralisation rates for the H and HP treatments increased more rapidly than that of the CK (p < 0.05), with increases of 27.6% and 54.4%, respectively. Results from field experiments (soil microbial biomass carbon content) supported this result. Compared with the CK, the H and P treatments rapidly increased soil labile organic carbon (LOC). The LOC content for the H treatment was 28.9% and 21.6% higher than that of the CK after 30 and 90 days, respectively (p < 0.05), whereas the LOC content for the P treatment was 32.8% and 20.2% higher than that of the CK after 60 and 90 days, respectively (p < 0.05). Redundancy analyses revealed that cultivation vs fallow treatments affected how polymer materials transform soil organic carbon. Cultivation allowed humic acid to improve soil aggregate mechanical-stability, promoting microbial decomposition of carbon and increasing organic carbon content. Modified polymer improved soil aggregate water-stability and reduced aggregate destruction, increasing the proportion of soil organic carbon that can be easily oxidised.

为了探究PPMn型水溶肥混合棉粕腐植酸肥施用对棉田土壤和棉花产量的影响,通过红外光谱和扫描电镜分析两种新型水溶肥的官能团特征和外观特征,并利用田间小区试验研究了两种新型水溶肥对棉田土壤物理性质及团聚体、棉花产量和肥料利用率的影响。结果表明:施用棉粕腐植酸肥（H）、PPMn型水溶肥（P）和两种新型水溶肥混合（HP）对改善土壤物化结构和提升棉花产量均优于常规水溶肥（S）和不施肥（CK）,其中HP处理效果最好。HP处理使土壤容重降低8.15%,土壤孔隙度增加7.49%,有效降低了＜0.25mm土壤团聚体所占比例,显著提升氮磷钾的农学利用效率,棉花产量相对于其他处理增加7.5%~41.0%。

The effects of three years continuous application of different rates of bio-organic fertilizer (BOF) were evaluated on three kinds of the counts of soil microbes, microbial metabolic activity and disease index of verticillium wilt through greenhouse pot experiments. The results showed that, the BOF not only reduced the occurrence of verticillium wilt in cotton and decreased the counts of Verticillium dahliae, but also improved the number of fungi, bacteria, actinomycetes, and microbial activity. The number of V. dahliae reduced gradually and fungi, bacteria, actinomycetes and average well color development (AWCD) firstly increased and then decreased with increasing the amount of fertilization in different organic matter content of soil. The number of V. dahliae was significantly increased by three years of fertilization. It showed that application of bio-organic fertilizer only delays the growth in the number of pathogen in soil within a certain time. The numbers of bacteria, actinomycetes were increased and the number of fungi was slightly reduced with increase of fertilization period. Application of bio-organic fertilizer made AWCD significantly higher than no fertilization (CK). By cluster analysis and principal component analysis, the results showed that the classification similar to disease index of various treatments, and it coincided with the number of microorganisms and AWCD values. BOF not only can control and improve the metabolic characteristics of soil microbial communities, but also maintain a high soil biological activity. (C) 2016 Friends Science Publishers

通过温室盆栽试验,研究了连续3年在不同土壤中施用不同量的生物有机肥的土壤养分、微生物生物量、酶活性及棉花各器官干物质量的变化.结果表明:连续3年施用生物有机肥,3种土壤的养分、酶活性、微生物量和各器官干物质量均有不同程度的提高.随着其用量的增加,土壤养分、微生物量及脲酶活性也在增加,土壤pH则相反,土壤蔗糖酶、多酚氧化酶、蛋白酶活性表现先上升后下降的趋势,且在不同土壤施用生物有机肥10～ 30 g/kg时基本达到最高,过氧化氢酶活性无显著变化.高、中、低有机质含量的土壤的棉花各器官干物质量分别在施用生物有机肥10～ 20、20～ 30、40 g/kg时基本达到最高.随着施肥年限的延长,3种土壤微生物生物量碳、氮均表现为先降低后升高的趋势,土壤酶活性则变化差异较大.通过在不同有机质含量土壤中施肥与不施肥比较发现,本底有机质含量越低的土壤,施肥较不施肥的土壤养分、脲酶、蔗糖酶、蛋白酶活性及微生物量增加幅度越大.

In this study we evaluated the effects of different rates of bio-organic fertilizer(BOF) in soil with different organic matter content on Verticillium dahliae,disease index,dry matter weight of plant,soil microbes and microbial biomass.The results showed that the dry matter weight of plant and soil microbial biomass were increased with amount increase of fertilization in soil with the different organic matter content,while the number of soil microorganisms increased first and then decreased.The result was the highest in the high organic matter content of soil with application of bio-organic fertilizer 10~20 g/kg and both in medium and low organic matter content of soil with application of bio-organic fertilizer 20~30 g/kg.Application of bio-organic fertilizer could significantly reduce the disease index of cotton Verticillium Wilt,and control effect was between 21.7%~75.0%.The control effect was the highest(52.6%) in the high organic matter content of soil with application of bio-organic fertilizer 20 g/kg,and the best(75.0%,55.0%) both in medium and low organic matter content of soil with application of bio-organic fertilizer 30 g/kg.In short,the scientific and rational fertilization not only is good for the microbial flora to a healthy and reasonable direction,but also minimizes the disease of cotton,and provide good protection for cotton growth.

The labile organic matter and enzyme activities of urease,protease,invertase,catalase and polyphenol oxidase were studied in soils treated with different rates of bio-organic fertilizer on soils which contained different organic matter during seedling of cotton.The results showed that:The labile organic matter and CMI were significantly increased when the organic fertilizer application rate increased in different soil.Among them,high organic matter content of soil(A)application of bio-organic fertilizer 20 g/kg results were obvious;Medium organic matter content of soil(B)and Low organic matter content of soil(C)application of bio-organic fertilizer 30 g/kg,40 g/kg effect were remarkable.Fertilization of five soil enzyme activities were higher than the control(CK).And the proportional to the amount of soil enzyme activity and application.Compared with other treatments,the changed significantly were urease,invertase and polyphenol oxidase in the application of bio-organic fertilizer 10 g/kg,20 g/kg,but catalase,protease did not change significantly.Correlation analysis showed that the correlation coefficient of the organic matter and labile organic matter and CMI in the seedling stage of cotton were 0.831* *,0.542*and 60 days after emergence correlation coefficient were 0.928* *,0.635* *,which the most relevant were organic matter and labile organic matter.While the CMI and the labile organic matter and organic matter in the seedling stage of cotton were 0.542*,0.896* *and 60 days after emergence were 0.635* *,0.842* *,and the labile organic matter and CMI were more closely than organic matter.The significantly related were invertase,catalase,polyphenol oxidase and soil organic matter,labile organic matter in the seedling stage and after 60 days of cotton.It showed that the labile organic matter and soil enzyme activities to better reflect the fertility level.