施肥是提升土壤肥力促进作物增产的有效措施，长期不同施肥对土壤培肥的效果差别很大，依托中国农科院红壤实验站双季稻田连续38年不同施肥定位试验，研究了7种不同施肥处理CK（不施肥）；NPK（化学氮、磷、钾肥料）；M（腐熟牛粪）；NPKM（化学氮、磷、钾和牛粪）；NPM（化学氮、磷和牛粪）；NKM（化学氮、钾和牛粪）；PKM（化学磷、钾和牛粪）对水稻产量、稻田土壤肥力与养分表观平衡的影响。结果表明，各处理水稻年均产量由高到低为NPKM、NPM、NKM、PKM、M、NPK、CK，范围在6214-11562 kg hm²。长期有机无机配施处理（NPKM、NPM、NKM、PKM）较NPK的增产率分别为：22.58%、15.35%、10.53%、4.41%。长期有机无机配施处理（NPKM、NPM、NKM、PKM）的土壤有机碳、全氮、有效氮、速效钾含量均显著高于CK和NPK，其中有机肥配施氮磷肥处理的NPKM、NPM、PKM土壤全磷和有效磷含量显著高于CK、NPK；NPKM处理的水稻年均产量（11562 kg hm²）、有机碳（20.88 g kg^-1）、土壤全氮（2.30 g kg^-1）、全磷（0.95 g kg^-1）、全钾（22.5 g kg^-1）、有效磷含量（38.94 mg kg^-1）均为各处理中最高，NKM处理土壤碱解氮含量（152.4mg kg^-1）和速效钾含量（151.00 mg kg^-1）为各处理最高。氮、磷施用量的增加导致土壤中氮、磷养分出现盈余，但NPKM处理相比其他处理能够有效降低盈余量；各处理土壤中钾素均表现为亏缺。相关性分析表明土壤SOC、TN、AN、TP、AP含量均与水稻产量显著相关（P<0.05），相关系数分别为0.428、0.496、0.518、0.501和0.438。本研究表明，相比单施化肥，长期有机肥配施化肥通过提升土壤肥力，促进土壤养分平衡，显著增加水稻产量，其中有机肥配施氮磷钾肥(NPKM)对于土壤肥力和水稻产量的提升效果最好。

 

该研究系统阐述了长期不同施肥对土壤剖面SOC和N库的影响，通过冗余分析了SOC团聚体组分及影响因素，三维表面分析深入理解剖面SOC和N库对作物产量的影响。与化肥处理相比，长期施用有机肥通过增加表土层 (0–20 cm）SOC输入、SOC储量、TN储量和土壤pH值来提高作物产量。不同施肥处理的SOC团聚体组分存在差异，所有处理SOC团聚体组分高低依次为矿物结合有机碳（mSOC）>粗自由颗粒有机碳（cfPOC）>物理保护有机碳（iPOC）>细自由颗粒有机碳（ffPOC）。施用有机肥处理的所有SOC组分含量均显著高于化肥处理。在不同SOC团聚体组分中，ffPOC对不同施肥处理的敏感性最高。单施有机肥（M）和有机无机肥配施（NPKM）显著提高了表层（0-20 cm）SOC和TN含量，与化肥处理相比，M和NPKM处理降低了深层土壤（80-100 cm）中的SOC和N含量，有利于减少养分垂直流动，从而减少养分的淋溶损失。

大豆炸荚（pod shattering）是大豆重要的生育特性，而在生产上则是影响栽培大豆产量的重要不利因素之一。本研究利用2个重组自交系群体（RIL，CY，华春2号×瓦窑黄豆；GB，桂早1号×巴西13），采用复合区间作图法（composite interval mapping，CIM），对大豆炸荚性状进行QTL定位。两个RIL群体在多个环境下共检测到14个与大豆炸荚相关的QTL，分布于大豆的01、03、03、04、05、05、07、12、14、16、17、18、20和20号染色体上，LOD值介于2.64-44.33，表型解释率为1.33%-50.85%。位于第16号染色体上的一个QTL（qPS16-1）与之前已报道的一个主效QTL（qPDH1）能够高度重叠，在这个区间内能够检测到8个基因，包含一个已知的功能基因Pdh1。另有10个QTL为本次实验鉴定的与大豆炸荚相关的新位点，LOD值介于2.55-4.24，表型解释率为1.33%-2.60%。在这之中，4个QTL位点（qPS01-1、qPS03-2、qPS05-1和qPS07-1）能够在两个环境中被检测到，说明它们是与大豆炸荚相关的环境稳定的QTL新位点，结合GO富集分析、公共数据库基因差异表达谱和基因注释等方法，最终筛选到9个可能参与调控大豆炸荚性状的候选基因，但其具体功能仍待进一步验证。本研究的结果将有助于育种家们更好地了解大豆抗炸荚特性的遗传机制，为大豆抗炸荚分子育种提供理论依据。

Azospirillum brasilense与Pseudomonas fluorescens是应用广泛的植物根际促生菌。目前Azospirillum brasilense与Pseudomonas fluorescens对稻田土壤氮循环和水稻生长发育的影响尚不清楚。本研究通过两年田间试验（2016-2017）解析了Azospirillum brasilense与Pseudomonas fluorescens对水稻根际土壤氮素转化和供氮能力的影响，明确了Azospirillum brasilense与Pseudomonas fluorescens在稻田肥料减施增效中的作用。微生物接种包括4个处理，分别为生理盐水接种（对照，M₀），水稻幼苗接种Azospirillum brasilense（M_b），水稻幼苗接种Pseudomonas fluorescens（M_p），水稻幼苗接种Azospirillum brasilense与Pseudomonas fluorescens的混合物（M_bp）。氮肥施用水平包括4个处理，分别为0 kg N hm^-2（N₀）)，90 kg N hm^-2（N₉₀），180 kg N hm^-2（N₁₈₀），270 kg N hm^-2 （N₂₇₀）。结果表明，与M₀相比，M_bp与M_p处理显著增强了水稻根际土壤氨化作用强度，高氮条件下提升作用更显著。与M₀相比，M_bp与M_b处理显著增强了水稻根际土壤固氮酶活性，低氮条件下提升作用更显著。接种用的Azospirillum brasilense与Pseudomonas fluorescens不参与水稻根际土壤的硝化和反硝化过程。根际促生菌与氮肥的交互作用对土壤呼吸速率与微生物量氮有显著影响。在M_bp处理中，N₉₀、N₁₈₀、N₂₇₀处理的土壤供氮能力与水稻产量无显著差异。水稻幼苗接种Azospirillum brasilense与Pseudomonas fluorescens的混合物，可将该地区氮肥施用量降至90 kg N hm^-2。

Soil productivity (SP) without external fertilization influence is an important indicator for the capacity of a soil to support crop yield. However, there have been difficulties in estimating values of SPs for soils after various long-term field treatments because the treatment without external fertilization is used but is depleted in soil nutrients, leading to erroneous estimation. The objectives of this study were to estimate the change of SP across different cropping seasons using pot experiments, and to evaluate the steady SP value (which is defined by the basal contribution of soil itself to crop yield) after various longterm fertilization treatments in soils at different geographical locations. The pot experiments were conducted in Jinxian of Jiangxi Province with paddy soil, Zhengzhou of Henan Province with fluvo-aquic soil, and Gongzhuling of Jilin Province with black soils, China. Soils were collected after long-term field fertilization treatments of no fertilizer (control; CK-F), chemical fertilizer (NPK-F), and combined chemical fertilizer with manure (NPKM-F). The soils received either no fertilizer (F0) or chemical fertilizer (F1) for 3–6 cropping seasons in pots, which include CK-P (control; no fertilizer from long-term field experiments for pot experiments), NPK-P (chemical fertilizer from long-term field experiments for pot experiments), and NPKM-P (combined chemical and organic fertilizers from long-term field experiments for pot experiments). The yield data were used to calculate SP values. The initial SP values were high, but decreased rapidly until a relatively steady SP was achieved at or after about three cropping seasons for paddy and fluvo-aquic soils. The steady SP values in the third cropping season from CK-P, NPK-P, and NPKM-P treatments were 37.7, 44.1, and 50.0% in the paddy soil, 34.2, 38.1, and 50.0% in the fluvo-aquic soil, with the highest value observed in the NPKM-P treatment for all soils. However, further research is required in the black soils to incorporate more than three cropping seasons. The partial least squares path mode (PLS-PM) showed that total N (nitrogen) and C/N ratio (the ratio of soil organic carbon and total N) had positive effects on the steady SP for all three soils. These findings confirm the significance of the incorporation of manure for attaining high soil productivity. Regulation of the soil C/N ratio was the other main factor for steady SP through fertilization management.

Received  27 October, 2017    Accepted  11 January, 2018

Nitrogen (N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better
understanding of the major pathways can assist in developing the best management practices. The aim of this study was
to evaluate the fate of N fertilizers applied to acidic red soil (Ferralic Cambisol) after 19 years of mineral (synthetic) and
manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined:
control (CK), chemical nitrogen and potash fertilizer (NK), chemical nitrogen and phosphorus fertilizer (NP), chemical nitrogen,
phosphorus and potash fertilizer (NPK) and the NPK with manure (NPKM, 70% N from manure). Based on the soil
total N storage change in 0–100 cm depth, ammonia (NH3) volatilization, nitrous oxide (N₂O) emission, N plant uptake, and
the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer
treatments (NK, NP and NPK) showed increased nitrate (NO₃^–-N) concentration with increasing soil depth, indicating higher
leaching potential. However, total NH3 volatilization loss was much higher in the NPKM (19.7%) than other mineral fertilizer
treatments (≤4.2%). The N₂O emissions were generally low (0.2–0.9%, the highest from the NPKM). Total gaseous loss
accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss
from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure
incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH₃
volatilization, which could be reduced by improving the application method. This study confirms that manure incorporation is an essential strategy in N fertilization management in upland red soil cropping system.

Dissimilatory Fe(III) reduction is an important process in the geochemical cycle of iron in anoxic environment.  As the main products of dissimilatory iron reduction, the Fe(II) species accumulation could indicate the reduction ability.  The effects of different green manures on Fe(III) reduction in paddy soil were explored based on a 31-year rice-rice-winter green manure cropping experiment.  Four treatments were involved, i.e., rice-rice-milk vetch (RRV), rice-rice-rape (RRP), rice-rice-ryegrass (RRG) and rice-rice-winter fallow (RRF).  Soils were sampled at flowering stage of milk vetch and rape (S1), before transplantation (S2), at tillering (S3), jointing (S4), and mature (S5) stages of the early rice, and after the harvest of the late rice (S6).  The contents of TFe_HCl (HCl-extractable total Fe), Fe(II)_HCl (HCl-extractable Fe(II) species) and Fe(III)_HCl (HCl-extractable Fe(III) species) were measured.  The correlations among those Fe species with selected soil environmental factors and the dynamic characteristics of Fe(II)_HCl accumulation were investigated.  The results showed that TFe_HCl in RRF was significantly higher than those in the green manure treatments at most of the sampling stages.  Fe(II)_HCl increased rapidly after the incorporation of green manures in all treatments and kept rising with the growth of early rice.  Fe(II)_HCl in RRG was quite different from those in other treatments, i.e., it reached the highest at the S2 stage, then increased slowly and became the lowest one at the S4 and S5 stages.  Fe(III)_HCl showed oppositely, and Fe(II)_HCl/Fe(III)_HCl performed similarly to Fe(II)_HCl.  The maximum accumulation potential of Fe(II)_HCl was significantly higher in RRF, while the highest maximum reaction rate of Fe(II)_HCl accumulation appeared in RRG.  Significant correlations were found between the indexes of Fe(II)_HCl accumulation and soil pH, oxidation-reduction potential (Eh) and total organic acids, respectively.  In together, we found that long-term application of green manures decreased the TFe_HCl in red paddy soils, but promoted the ability of Fe(III) reduction, especially the ryegrass; Fe(II)_HCl increased along with the growth of rice and was affected by soil conditions and environmental factors, especially the water and redox ability.

On the basis of a long-term (30 years) field experiment that involved four rotation systems, rice-rice-winter fallow (RRF), rice-rice-ryegrass (RRG), rice-rice-rape (RRP), and rice-rice-milk vetch (RRV), this study described the effects of green manure on the microbial communities in the red paddy soils using 454 pyrosequencing for the 16S rRNA gene. The Chao1 richness and non-parametric Shannon’s index increased in all soil samples that received green manure treatments. The communities’ structures with the green manure applications were significantly dissimilar from that under the winter fallow. Using Metastats tests, many genera in the RRG, RRP and RRV soils were significantly different from those in the RRF soil, including a number of genera that functioned in the nitrogen and sulfur cycles. Analyses of the genera with these functions revealed the shifts in microbial ecosystem functions after long-term green manuring. Changes in the microbial communities increased the ammonium supply and decreased the soil acidification in green-manure-amended soils. Together, these data suggested powerful effects of green manure on both the microbial communities and the biogeochemical cycle driven by the shifts in bacterial functional groups.

Combined with remote sensing data and meteorological data, cold damage risk was assessed for planting area of double cropping rice (DCR) in Hunan Province, China. A new methodology of cold damage risk assessment was built that apply to grid and have clear hazard-affected body. Each station cold damage annual frequency and average annual intensity of cold damage was calculated by using 1951-2010 station daily mean temperature and simple cold damage identification index. On this basis, average annual cold damage risk index was obtained by their product. The spatial analysis models of cold damage risk index about double-season early rice (DSER) and double-season later rice (DSLR) were established respectively by the relation of average annual cold damage risk index and its geographic factors. Critical threshold of level of average annual cold damage risk index for DSER and DSLR were respectively divided by the correlative equation of cold damage annual frequency and average annual intensity of cold damage. 2001-2010 planting area of DCR, acquired by time series analysis of MOD09A1 8-d composite land surface reflectance product, was as target of assessment. The results show average annual intensity of cold damage is exponential function of cold damage annual frequency, average annual cold damage risk index is directly proportional to cold damage cumulant and cold damage annual frequency, and is inversely proportional to happen times of cold damage and the square of statistical time sequence length. Cold damage risk of DSER is higher than DSLR in Hunan Province. In the 10-yr stacking map, DCR planting in low risk area accounted for 11.92% of total extraction area, in moderate risk area accounted for 69.62%, in high risk area accounted for 18.46%. According to the cold damage risk assessment result, DCR production can be guided to reduce cold damage losses.

Adequate freshwater supply has become an issue of increasing local and international concern. Reducing water use in agriculture, which is the largest water using sector of the economy, is both important and urgent. The aim of this paper was to quantify how recent cropping pattern changes have influenced water resources in the great Beijing metropolitan area, an expanding megacity which also includes rural counties. Crop production affects blue water use through water consumption and water pollution, the latter assessed here using a critical dilution method. From 1990 to 2010, the total blue water used by crop production declined due to a decrease in overall cropped area, initially in response to local government policies favouring urban development. However, the average blue water use per hectare increased from 2 112 m3 ha-1 yr-1 in 1990 to 2 764 m3 ha-1 yr-1 in 2003, largely as the result of a transition from cereal to vegetable crops, and in particular an increase in intensively managed plastic and glass covered vegetable production systems. Current policies aim to conserve agricultural land, in the interests of food security, and to stimulate cereal production systems with higher ecosystem services provision. As such, in 2010 the average blue water use was 2 425 m3 ha-1 yr-1. These results demonstrate that cropping pattern changes in peri-urban regions and rural communities surrounding the Beijing metropolitan area can have a substantial impact on water resources. They also highlight the tradeoffs between food production and urban and industrial water supply and the need for integrated policy development.

A long-term field experiment was established to determine the influence of mineral fertilizer and organic manure on soil fertility. A tract of red soil (Ferralic Cambisol) in Qiyang Red Soil Experimental Station (Qiyang County, Hunan Province, China) was fertilized beginning in 1990 and N2O and CO2 were examined during the maize and wheat growth season of 2007-2008. The study involved five treatments: organic manure (NPKM), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), and control (CK). Manured soils had higher crop biomass, organic C, and pH than soils receiving the various mineralized fertilizers indicating that long-term application of manures could efficiently prevent red soil acidification and increase crop productivity. The application of manures and fertilizers at a rate of 300 kg N ha-1 yr-1 obviously increased N2O and CO2 emissions from 0.58 kg N2O-N ha-1 yr-1 and 10 565 kg C ha-1 yr-1 in the CK treatment soil to 3.01 kg N2O-N ha-1 yr-1 and 28 663 kg C ha-1 yr-1 in the NPKM treatment. There were also obvious different effects on N2O and CO2 emissions between applying fertilizer and manure. More N2O and CO2 released during the 184-d maize growing season than the 125- d wheat growth season in the manure fertilized soils but not in mineral fertilizer treatments. N2O emission was significantly affected by soil moisture only during the wheat growing season, and CO2 emission was affected by soil temperature only in CK and NP treatment during the wheat and maize growing season. In sum, this study indicates the application of organic manure may be a preferred strategy for maintaining red soil productivity, but may result in greater N2O and CO2 emissions than treatments only with mineral fertilizer.