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Zhao S.,Chinese Academy of Agricultural Sciences | Li K.,Hebei Academy of Agricultural and Forestry science | Zhou W.,Chinese Academy of Agricultural Sciences | Qiu S.,Chinese Academy of Agricultural Sciences | And 3 more authors.
Agriculture, Ecosystems and Environment | Year: 2016

Field nutrients management practices influence soil biological properties and organic matter fractions. A long-term experiment (30-year) was conducted to investigate changes in soil microbial community, enzyme activities and organic carbon fractions under straw return in north-central China. Treatments included no-fertilizer control (CK) and maize straw return at rates of 0 (S0), 2250 (S1), 4500 (S2), and 9000kgha-1 (S3) under combined nitrogen and phosphorus fertilization. All fertilization treatments increased total phospholipid fatty acid (PLFA) and the abundances of Gram-negative (Gm-) bacteria and fungi over the CK treatment. The S3 treatment increased total PLFA compared with the S0 treatment. The S2 and S3 treatments increased Gm- bacterial abundance by 11.6 and 9.3%, respectively, and increased fungal abundance by 68.2 and 113.6%, respectively, compared with the S0. Fertilization increased the activities of β-glucosidase (BG), β-xylosidase (XYL), and N-acetyl-glucosaminidase (NAG) over the CK. The S2-S3 increased the activities of BG, XYL, and NAG by 10.5-20.7, 19.0-32.5, and 21.6-32.8% compared with the S0, respectively. Although the S1 and S3 had lower activities of phenol oxidase than the CK, the activities did not differ among the S0-S3 treatments. The S0-S3 treatments increased the concentration of total organic C (TOC) than the CK, and the S2-S3 increased TOC than the S0. There were no differences in soil light fraction (LF) and the light fraction organic C (LFOC) among the CK, S0, and S1. The LF and LFOC in the S2 increased by 14.7 and 33.9%, respectively, and these values in the S3 increased by 48.0 and 81.3%, respectively, relative to the S0. The S0-S3 treatments increased the heavy fraction organic C (HFOC) over the CK and the HFOC in the S2-S3 increased by 39.2-43.1% compared with the S0. The LFOC/TOC ratio was lower than the HFOC/TOC ratio for each treatment. Overall, low rates of straw return did not affect, while high rates of straw changed microbial community structure and increased the activities of most hydrolytic enzymes and the concentration of LFOC and HFOC under chemical fertilizer application. © 2015 . Source


He P.,Chinese Academy of Agricultural Sciences | He P.,CAAS IPNI Joint Laboratory for Plant Nutrition Innovation Research | Yang L.,Chinese Academy of Agricultural Sciences | Xu X.,Chinese Academy of Agricultural Sciences | And 8 more authors.
Field Crops Research | Year: 2015

Potassium (K) fertilizers are non-renewable resources and cannot be synthesized from other chemicals. Understanding soil K status in China is crucial for the efficient use of K resources, and the resulting food security and resource sustainability. We analyzed temporal and spatial changes in soil K from 58,559 soil samples, and yield responses from 2055 field experiments compiled from the International Plant Nutrition Institute (IPNI) China Program database from 1990 to 2012. The results indicated that on average soil available K increased from 79.8mgL-1 in the 1990s, to 93.4mgL-1 in the 2000s, with the increase for cash crops faster than that for grain crops. In fact the average increase in soil available K over time was attributed to increases in soil K for cash crop fields with high K fertilizer application (1.4 to 2.6 times more than for grain crops). The study found great variation in soil available K across different regions and over time in China. Soil available K varied over space with values of 76.8, 99.8, 118.0, 83.9 and 81.3mgL-1 for northeast (NE), north central (NC), northwest (NW), southeast (SE) and southwest (SW), respectively. While no difference in soil available K over the time period of the study was observed in NE China, the values increased by 34.8%, 17.9% and 30.2% for NC, SE and SW, respectively, and decreased by 75.9% for NW China between the 1990s and 2000s. Great temporal and spatial variation existed for relative yield as well, which followed similar trends to soil available K. Potassium fertilizer application continued to be recommended for grain crops due to the low soil available K falling short of critical values, and cash crops where a larger yield response to K fertilizer has been recorded. This great variation observed in soil available K across the different regions in China demonstrated the urgent need for site-specific K nutrient management. © 2015 Elsevier B.V. Source


Zhao S.,Chinese Academy of Agricultural Sciences | He P.,Chinese Academy of Agricultural Sciences | He P.,International Plant Nutrition Institute IPNI | He P.,CAAS IPNI Joint Laboratory for Plant Nutrition Innovation Research | And 6 more authors.
Field Crops Research | Year: 2014

Understanding the changes in soil potassium (K) and crop yield under K fertilization and straw return is important for proper K fertilizer management. A field experiment involving a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation was conducted to study the effects of long-term (20-year) K fertilization and straw return on soil K and crop yield in north-central China. Fertilization treatments included: nitrogen and phosphorus fertilizers (NP), NP plus wheat straw (NPS), NP and K fertilizers (NPK), and NPK plus wheat straw (NPKS). Annual soil K budget increased with increasing K inputs (including fertilizer K and straw K) in the order of NP. <. NPS. <. NPK. <. NPKS, and further increased after maize straw returned since 2008. The NP and NPS treatments decreased soil available K and slowly available K below the initial levels, K fertilization and/or straw return increased available K and slowly available K in the top 30. cm soil over the NP treatment. Fertilization did not significantly alter total K in the 0-100. cm depths, but in the 0-10. cm soil layer, the NP, NPS, and NPK treatments decreased total K by 4.3%, 3.4%, and 0.4% than the initial concentration, respectively. Compared with the NP treatment, K fertilization and/or straw return increased crop yields in most cases, and the effect of K inputs on yield increase was greater for maize than wheat. Additionally, increased straw return enhanced soil organic carbon (SOC) beyond the NP treatment, and SOC decreased with depths between 0 and 40. cm soil; however, fertilization did not change SOC below 40. cm. In conclusion, K fertilization and/or straw return alleviated soil K depletion and increased soil K fertility; crop yields increased with increasing K inputs, and yield response of maize to K fertilization was greater than wheat. © 2014 Elsevier B.V. Source


Zhao S.,Chinese Academy of Agricultural Sciences | Zhao S.,CAAS IPNI Joint Laboratory for Plant Nutrition Innovation Research | Qiu S.,Chinese Academy of Agricultural Sciences | Qiu S.,CAAS IPNI Joint Laboratory for Plant Nutrition Innovation Research | And 7 more authors.
Agriculture, Ecosystems and Environment | Year: 2014

Excessive nitrogen (N) fertilization is widespread in intensive double cropping system in China and assessment of changes in soil quality and crop production under various N application rates is important for N fertilizer management. A wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation experiment was conducted from 2009 to 2012 in north-central China to study the effects of high N fertilization rates on soil chemical properties and microbial community, and to evaluate soil sustainability under reduced N inputs. The N rates tested were 0 (N0), 70 (N1), 140 (N2), 210 (N3), 280 (N4) and 350kgNha-1 (N5) in the maize season, and 0 (N0), 60 (N1), 120 (N2), 180 (N3), 240 (N4) and 300kgNha-1 (N5) in the wheat season, respectively. Soil NO3 --N in the 0-100cm depth, and soil electrical conductivity (EC) and nitrification potential in the 0-20cm were significantly increased, whilst pH in the 0-20cm was decreased with increasing N application rates. In addition, the high rates of N fertilization (N4 and N5) increased soil fungal abundance and the ratio of fungi to bacteria compared with lower N rates and the N control; however, N rates did not influence abundance of soil bacteria and actinomycetes, and total phospholipid fatty acid (PLFA). The application of N at 180 and 210kgNha-1 during the wheat and maize seasons, respectively, sustained high yields and enhanced accumulated N recovery efficiency (RENac) compared with higher N rates. Our results indicated that the high N inputs degraded soil quality and changed microbial community structure. A 12.5-40% reduction in the farmers' conventional N application rates was practical to reduce excess N input while maintaining the sustainability of the wheat-maize cropping system in north-central China. © 2014 Elsevier B.V. Source


Ma J.,Chinese Academy of Agricultural Sciences | He P.,Chinese Academy of Agricultural Sciences | He P.,International Plant Nutrition Institute IPNI | He P.,CAAS IPNI Joint Laboratory for Plant Nutrition Innovation Research | And 13 more authors.
Field Crops Research | Year: 2016

Mineral fertilizers have played a critical role in increasing cereal crop production in China. However, the use of fertilizer at rates in excess of crop removal or to support soil health has resulted in serious environmental problems, this hindering sustainable agriculture development. In order to support crop production and reduce potential environmental risks, it is essential that every effort is made to promote an efficient and effective use of phosphorus (P) resources. In this paper, the temporal and spatial changes of soil available P was analyzed using 59,956 soil samples, combined with the results of 4837 field experiments compiled from the International Plant Nutrient Institute (IPNI) China program database from 1990 to 2012. The results demonstrated that soil available P content showed an increasing trend with a slope of 1.51 from 1990 to 2012. However, this trend for all samples was separated into cash crops (with a slope of 2.75) and grain crops (with a slope of 0.76) revealing that it was cash crops that were primarily responsible for the increasing trend. Field trail results revealed that it was the high P fertilizer application rates to cash crops that resulted in the increase of soil available P. On average, for all crops, the soil analysis data showed that soil available P increased from 17.09 mg L-1 in the 1990s (from 1990 to 2000) to 33.28 mg L-1 in the 2000s (from 2001 to 2012), again mainly due to the large increase in cash crop area in China. For relative yield, there was little to no variation across regions (with mean values of 87.8%, 87.8%, 84.4%, 88.1% and 86.0% for the NE, NC, NW, SE and SW regions, respectively), but the trend of variation showed great differences in those same regions from the 1990s to the 2000s. The relative yield for grain crops in the NE, NC, SE and SW increased by 2.6%, 7.9%, 6.9% and 8.6%, but decreased by 4.9% in the NW from the 1990s to the 2000s. The relative yield for cash crops decreased by 6.7%, 6.0% and 1.6% for the NE, SE and SW regions, but increased by 8.3% and remained unchanged for the NC and NW regions, respectively. The great variation observed in soil available P across the different regions in China demonstrated the urgent need for site-specific P nutrient management. In conclusion, while P fertilizer application should meet the requirements for all types of crops, it must be managed to avoid the potential for negative environmental impacts. © 2016 Elsevier B.V. Source

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