Nitrogen and Phosphorus Runoff Losses from Orchard Soils in South China as Affected by Fertilization Depths and Rates

Fertilizers are heavily applied in orchards of the hilly and mountainous topography of South China and may increase nutrient loadings to receiving waters.A simple runoff collecting system was used to measure the effects of different fertilization treatments on total N and P concentrations of surface runoff in a Chinese chestnut (Castanea mollissima Blume) orchard in Dongyuan County,Guangdong Province,China.In such orchards,fertilizer was typically applied in two short furrows or pits on either side of each tree.Treatments included three application depths (surface,10cm and 20 cm),and three application rates (low,median and high).Results showed that 90.5% of the runoff water samples had a total N concentration higher than 0.35 mgL^(-1) and 54.2% had a total P concentration higher than 0.1 mgL^(-1).Fertilizer application at all depths and at all but the lowest rate significantly increased total N and P concentrations in runoff water.Fertilization with chemical compound fertilizer at a soil depth of 20cm produced significantly lower (P<0.05) total N concentration in runoff than both surface and 10-cm depth fertilization,and significantly lower (P<0.05) total P concentration in runoff than surface fertilization.Total N and P concentrations in runoff significantly increased with the application rate of organic fertilizers.With the exception of total P concentrations,which were not significantly different between the control and fertilization at a rate of 119 kg P ha-1 in organic form,all the other fertilization treatments produced significantly higher total N and total P concentrations in runoff than the control.A fertilization depth≥20cm and an application rate≤72 kg N ha^(-1) or 119 kg P ha^(-1) for compound organic fertilizer was suggested to substantially reduce N and P runoff losses from hillslope orchards and to protect receiving waters in South China.

Nitrogen Runoff and Leaching Losses During Rice-Wheat Rotations in Taihu Lake Region,China

Although nitrogen （N） loss through runoff and leaching from croplands is suspected to contribute to the deterioration of surrounding water systems, there is no conclusive evidence for paddy soils to prove this hypothesis. In this study, field plot experiments were conducted to investigate N losses through runoff and leaching for two consecutive years with 3 N fertilization rates in rice （Oryza sativa L.）-wheat （Triticum aestivum L.） rotations in the Taihu Lake region, China. A water collection system was designed to collect runoff and leachates for both the rice and wheat seasons. Results showed that dissolved N （DN）, rather than particulate N （PN）, was the main form of N loss by runoff. The NO3^--N concentration in runoff was between 0.1 and 43.7 mg L^-1, whereas the NH4^＋-N concentration ranged from below detection limit to 8.5 mg L^-1. Total N （TN） loads by runoff were 1.0-17.9 and 5.2-38.6 kg ha^-1 during rice and wheat seasons, respectively, and the main loss occurred at the early growing stage of the crops. Nitrogen concentrations in leachates during the rice seasons were below 1.0 mg L^-1 and independent of the N application rate, whereas those during the wheat season increased to 8.2 mg L^-1 and were affected by the fertilizer rate. Annual losses of TN through runoff and leaching were 13.7-48.1 kg ha^-1 from the rice-wheat cropping system, accounting for 5.6%-8.3% of the total applied N. It was concluded that reduction in the N fertilization rate, especially when the crop was small in biomass, could lower the N pollution potential for water systems.

Impact of fertilization on chestnut growth, N and P concentrations in runoff water on degraded slope land in South China

Growing fruit trees on the slopes of rolling hills in South China was causing serious environmental problems because of heavy application of chemical fertilizers and soil erosion. Suitable sources of fertilizers and proper rates of applications were of key importance to both crop yields and environmental protection. In this article, the impact of four fertilizers, i.e., inorganic compound fertilizer, organic compound fertilizer, pig manure compost, and peanut cake （peanut oil pressing residue）, on chestnut （Castanea mollissima Blume） growth on a slope in South China, and on the total N and total P concentrations in runoff waters have been investigated during two years of study, with an orthogonal experimental design. Results show that the organic compound fertilizer and peanut cake promote the heights of young chestnut trees compared to the control. In addition, peanut cake increases single-fruit weights and organic compound fertilizer raises single-seed weights. All the fertilizers increased the concentrations of total N and total P in runoff waters, except for organic compound fertilizer, in the first year experiment. The observed mean concentrations of total N varied from 1.6 mg/L to 3.2 mg/L and P from 0.12 mg/L to 0.22 mg/L, which were increased with the amount of fertilizer applications, with no pattern of direct proportion. On the basis of these experiment results, organic compound fertilizer at 2 kg/tree and peanut cake at 1 kg/tree are recommended to maximize chestnut growth and minimize water pollution.

Winter Runoff of Nitrogen and Phosphorus from a Rotational Pen Design with Suckler Cows

Keeping beef cattle outdoors during winter reduces costs and improves animal welfare, but increases the risk of nitrogen (N) and phosphorus (P) runoff losses. This study evaluated a rotational pen design on grassland with two groups of suckler cows given access to an expanding staying area and a new feeding area each week (72 cattle ha-1), with one month’s stay per pen. The spatial distribution of excreta and effects on N and P surface runoff was evaluated during six months. The total excreta loads corresponded to 500 kg·N·ha-1 and 50 kg·P·ha-1. New feeding areas did not distribute excretions evenly, which resulted in the highest proportion of excretions (31%) occurring in the first week’s sub-area. The topsoil had significantly higher amounts of mineral-N, mainly as NH4-N (29 - 81 kg·ha-1), than an unaffected area (13 kg·ha-1). Mean total runoff losses were similar for both groups (1.4 kg·P·ha-1 and 9.0 kg·N·ha-1). Around 78% of N and 70% of P runoff losses occurred during the month with cattle present. During the first two weeks with heavy rain, N and P runoff losses were 50% higher from an area with suckler cows than a corresponding vegetated sub-area without cows. The study design did not provide a sufficient distribution of excretions and a high animal density in combination with trampling resulted in unacceptable N and P run-off losses. An environmentally friendly design would need to include frequent moving of all equipment and access to larger areas.

Reviews on Agricultural Nonpoint Source Pollution Monitoring Techniques and Methods

Farmland nutrient loss has become one of the main reason causing agri- cultural nonpoint source pollution and water nitrogen, phosphorus eutrophication. Agricultural nonpoint source pollution monitoring techniques and methods are very important in agricultural nonpoint source pollution control. This paper reviews the various monitoring techniques of agricultural non-point source pollution, including runoff pollutant monitoring, leaching pollutant monitoring and on-line monitoring. The runoff pollutant monitoring methods are mainly included artificial simulation of rain- fall runoff method, flow meter method, weir method and volumetric method. The leaching pollutant monitoring methods are mainly included leaching plate method, leaching gutter method, leakage pooling method, pumping filter pipe method and simulating soil column method. Although online monitoring of farmland nutrient loss still exists some technical bottlenecks and economic limitations, it is the future di- rection of development.

不同植被盖度香根草减少沟渠侵蚀和C,N,P流失的有效性

[目的]探究植物在降低沟渠侵蚀及减少C,N,P流失方面的影响,为流域沟渠侵蚀防控及污染物治理提供技术支撑。[方法]以中国南亚热带集约化蔗区那辣流域沟渠为研究对象,在沟渠中植入不同植被盖度:全部裸露,植被覆盖度为0(BG);部分覆盖,植被覆盖度1%~40%(SC);大部分覆盖,植被覆盖41%~80%(MC);全覆盖,植被覆盖81%~100%(CC)的草本植物香根草。对4—10月的植草沟渠在降雨后定期实地调查和监测,量化不同植被盖度下沟渠的侵蚀与养分流失特征。[结果](1)4—10月,不同植被盖度沟渠宽度、侵蚀量和C,N,P流失量随着时间的增加逐渐增加,大小均表现为:BG>SC>MC>CC。(2)相比于BG,SC,MC和CC沟渠侵蚀量分别降低了37.01%,71.60%和75.04%;C流失量分别降低了35.56%,70.91%和75.23%,N流失量分别降低了35.89%,71.01%和74.39%;P流失量分别降低了34.22%,70.59%和77.01%。(3)相关性分析表明,沟渠侵蚀量与覆盖度和植物根系密度均达到极显著负相关关系(p<0.01),分别解释了沟渠侵蚀变化的91.94%和89.23%。[结论]流域内植草,随着沟渠植被盖度的增加,沟蚀量和养分流失量逐渐降低,且植被盖度在处理MC和CC之间差异不显著。这一结果在改善其他水源区沟渠的侵蚀及降低污染物方面可提供参考依据。

Recovery of Essential Plant Nutrients from Biofuel Residual

Essential plant nutrients contained in residues and wastes generated during biofuel processing can be recovered for further production of bioenergy biomass. The objective of this study was to determine the relative agronomic efficiency of “processed” biofuel residual (PBR). Liquid biofuel residual was “processed” by precipitating phosphate and ammonium in the residual with magnesium into a struvite-like material. Then, in a series of greenhouse experiments, we evaluated the fertility potential of PBR, using sweet sorghum (Sorghum bicolor (L.) Moench), as a test bioenergy crop. We compared the agronomic effectiveness of PBR to inorganic commercial fertilizers, biosolids, and poultry manure as nutrient sources. The sources were either applied alone or in combination with supplemental essential plant nutrients (S, K, Mg, and micronutrients). In each of the greenhouse experiments, the crop was grown for 12 wk on soil of minimal native fertility. After each harvest, sufficient water was applied to the soil in each pot over a 6-wk period to yield ~2 L (~one pore volume) of leachate to assess potential total N and soluble reactive phosphorus (SRP) losses. Dry matter yields from the PBR treatment applied alone were significantly greater than yields from inorganic fertilizers, biosolids, and poultry manure treatments applied alone, and similar to yields obtained when the supplemental essential plant nutrients were added to the inorganic fertilizer, biosolids, and manure treatments. Leachate N and SRP concentrations from the PBR treatment were significantly lower than in the treatments with inorganic fertilizers, poultry manure, and biosolids. We conclude that PBR can substitute for inorganic fertilizers and other organic sources of plant nutrients to produce bioenergy biomass cheaply, without causing offsite N and P losses in vulnerable soils.

麦秸还田对水稻产量及地表径流NPK流失的影响

在大田试验条件下,以水稻品种运2645为供试材料,设置常规处理(A)、麦秸还田(B)、麦秸还田减肥(C)、肥料运筹(D)和旋耕(E)5个处理组合,研究不同处理对水稻产量及农田地表径流NPK流失的影响。结果表明:(1)麦秸还田使水稻产量比常规处理增加3.0%左右;(2)试验年度稻季农田总地表径流水量为4.3×103m3·hm-2;(3)麦秸还田减肥和麦秸还田处理比其处理明显降低农田地表径流水体NPK流失量,不同处理地表径流总N流失量由低到高依次为麦秸还田减肥、麦秸还田、常规处理、肥料运筹和旋耕,不同处理地表径流总P和K的流失量由低到高依次为麦秸还田减肥、麦秸还田、肥料运筹、常规处理和旋耕;(4)麦秸还田能够降低稻田地表径流NPK的流失率,但麦秸还田减肥处理由于流失量减小幅度远低于肥料施用量的减小幅度,其NPK流失率均表现为最高;(5)麦秸还田使水稻产量略有增加,使稻田地表径流水体NPK流失量和流失率均明显降低。

红壤小流域不同土地利用方式下土壤N,P流失特征研究

研究了次降雨过程中红壤小流域5种不同土地利用方式土壤N,P养分流失特征。结果表明,在降雨后,花生地、花-橘间作、橘园、板栗园和水田5种利用方式表层土壤N,P养分含量均有不同程度下降,其中花生地N,P含量下降最为明显,水田N,P含量降幅则最小;不同形态养分平均降幅依次为有效氮(5.49%)、有效磷(5.25%)、全氮(1.45%)、全磷(0.59%)。各样地地表径流中水溶态N,P养分含量花生地明显高于其他样地,而泥沙中N,P养分含量则以水田最高;各样地侵蚀泥沙中N,P养分有明显的富集现象,板栗园和橘园N,P养分富集率高于其他样地,水田N,P养分富集率最低。不同形态养分富集率也不同,全氮平均富集率为1.30,有效氮1.18,全磷1.11,有效磷1.38。侵蚀径流中N,P养分与表层土壤相同形态养分之间呈显著正相关。

三峡库区黑沟流域AnnAGNPS参数空间聚合效应

农业非点源污染物是长江三峡库区主要污染源之一,已造成令人关注的生态、环境和健康等问题,流域模型(AnnAGNPS)与GIS结合,为空间数据组织和模型参数空间聚合提供技术基础,是其预测和流域规划与管理的有效途径。三峡库区小流域条件下,基于临界源面积(CSA)和最小初始沟道长度(MSCL)值域设定,形成不同流域划分方案,空间离散单元(SDU)水平,即SDU大小及数量,影响输入参数空间聚合效应及模型输出结果。在黑沟小流域(144.4hm2)应用已校准AnnAGNPS模型,设定CSA和MSCL值域为0.5～15hm2及7.5～200m,10种SDU水平、流域尺度和条件下,结果表明:空间参数聚合程度和模型输出结果均随SDU尺度改变而发生变化。土地利用与土壤类型等参数具有明显的聚合效应,径流、泥沙和养分输出具有不同的SDU适宜水平和范围。SDU尺度聚合效应对径流量影响较小,而对泥沙、总N、总P模拟影响较大;径流量、泥沙、总N、总P模拟输出误差可接受SDU尺度范围分别为0.5～18、2～6、0.5～6hm2。因此,应用AnnAGNPS模型,更需要注意不同子模型所需要适宜的SDU尺度水平。

氮磷配施对坡地谷子吸N,P量及土壤养分流失的影响

氮磷配施对坡地谷子吸Ｎ，Ｐ量及土壤养分流失影响的研究表明：（１）Ｎ，Ｐ肥的不同配比均能增加谷子对Ｎ，Ｐ的吸收，增施Ｐ对Ｎ吸收的效果较高于增施Ｎ对Ｐ的吸收；（２）施Ｎ，Ｐ量的增加与泥沙中Ｎ，Ｐ富集率无相关关系；（３）作物生物量与土壤侵蚀量的相关系数为－０．９７２４；（４）增施Ｎ，Ｐ肥对土壤侵蚀和全量养分减少的程度远高于对径流量和速效Ｎ。

紫色土丘陵区非耕作季节不同种植模式下NP流失模型

为了解长江上游紫色土丘陵区非耕作季节N、P的流失特征,以长江上游紫色土丘陵区4种典型种植模式为研究对象,采用野外调查、室内分析和模型模拟相结合的方法,于2008年11月1日至12月31日研究了耕作季节后不同种植模式在每次降雨后的N、P流失特征及不完全混合模型的综合应用效果。结果表明,非耕作季节,紫色农耕地均表现出较大的N、P流失量,最大分别达到(0.491±0.079)kg·hm-2和(12.604±13.173)×10-3kg·hm-2。N的流失量均大于P的流失量,并且N、P主要通过地表径流流失。不同种植模式间N、P流失量有较大的差异,其中生姜种植模式的N、P流失量最大,大豆种植模式最小。不完全混合模型可很好应用于研究区域农耕地N、P流失。模型的有效系数均达到0.6以上,其中模拟N流失的有效系数高达0.958。这表明,非耕作季节农耕地N、P流失是区域农业面源污染的重要来源,不完全混合模型可成为该区域N、P流失预报和面源污染控制的重要手段。

Nitrogen Losses from Flooded Rice Field

A field microplot experiment was conducted during the tillering stage of paddy rice to investigate nitrogen(N) Iosses from flooded rice fields following fertilizer application. After application of ammonium bicarbonate,most of nitrogen in the floodwater was present as NH4-N and its concentration varied widely with time.Concentrations of both NO3-N and NO2-N in the floodwater were low due to the weakened nitrification.Under flooded anaerobic reducing conditions, soil solution concentrations of NO3-N and NH4-N were nothigh, ranging from 0.6 mg L-1 to 4.8 mg L-1, and decreased with soil depth. However, the groundwater wasstill contaminated with NO3-N and NH4-N. Rainfall simulation tests showed that the N losses via runoff inrice fields were closely related to the time intervals between fertilizer applications and rainfall events. Whena large rain fell for a short period after fertilizer application, the N losses via runoff could be large, whichcould have a considerable effect on surface water quality. Both irrigation and N fertilizer application mustbe controlled and managed with great care to minimize N losses via runoff from agricultural land.

福建省地表径流N、P流失系数的测算

通过对福建省12个地表径流监测点径流水中氮磷含量的分析,得出了福建省地表径流的N、P流失系数。结果表明:我省总氮流失系数为0.414%-7.862%,总磷流失系数为0.032%-1.314%。

Predictions of soil and nutrient losses using a modified SWAT model in a large hilly-gully watershed of the Chinese Loess Plateau

Hydrological models are effective tools for assessing the effects of soil and nutrient losses on land degradation.SWAT(Soil and Water Assessment Tool)model is widely used to simulate soil and nutrient losses caused by various management regimes.However,its performance of predicting nutrient loss has not been assessed adequately on the Loess Plateau.This study proposed a modified SWAT model by incorporating the modified Soil Conservation Service curve number method,the storm-based Chinese soil loss equation and the nutrient loss model.The observed daily data of runoff and sediment over 16 years and the monthly soluble phosphorus(P)and nitrate losses over 9 years and 4 years,respectively at the outlet of the upper Beiluo river(UBR)basin were used to assess the model performances.Global sensitivity and uncertainty analyses of parameters to runoff,sediment,soluble P and nitrate in the modified SWAT were conducted.The findings during calibration and validation showed that the modified SWAT was highly accurate in terms of model efficiency(calibration:0.83,0.83,0.48,and 0.49;validation:0.58,0.57,0.53,and 0.65)for runoff,sediment,soluble P loss and nitrate loss,respectively.High model efficiency indicated that the modified SWAT could accurately predict soil and nutrient losses at the river basin scale for the Loess Plateau.Moreover,the temporal variations from month to year and the spatial variations at the sub-basin scale for soil loss and the total N and P losses were analysed using the data simulated by the modified SWAT.The results indicated that the critical loss period occurred in July and August,and the Grain for Green project significantly affected the hydrological behaviour and reduced the soil and nutrient losses in the UBR basin.

基于DNDC模型的稻田氮素流失及其影响因素研究

稻田氮素流失是导致农业面源污染的主要原因之一。采用测坑定位实验获得的野外观测数据对DNDC模型模拟稻田氮素流失的可行性进行验证,同时重点采用模型的敏感性分析功能对影响稻田氮素流失的关键因素进行分析研究。结果表明:DNDC模型能够准确地模拟不同施肥条件下稻田的氮素流失和水稻产量,施肥和降雨是影响稻田氮素流失的主要因素,与稻田氮素流失呈正比。值得注意的是,在目前施肥水平下有机肥的施用对稻田氮素的渗漏流失无明显贡献。此外,稻田氮素的渗漏流失还与土壤硝态氮的含量呈正比,而与土壤有机碳含量和黏土比例呈反比。根据敏感性分析结果可知,在我国稻田目前的施肥水平下,降低施肥量、采用节水灌溉以及增施有机肥等措施均是减少稻田氮素流失的有效手段。

利用Vensim建立水稻田氮素迁移动态模拟模型及其验证分析

通过独立排灌系统的田间试验、自行设计的渗漏计研究在控水灌溉条件下大田不同氮肥水平的水稻氮素吸收、田面水氮素动态变化特征及氮素淋失规律.基于前人对氮素在稻田-作物-土壤及水体中的转化迁移途径的研究结果,用Vensim模拟软件构建稻田氮素迁移转化过程的动态模拟模型,利用2003年余杭农业科学研究所氮肥试验测定的相关数据对模型参数进行校验,再利用2006年富阳及杭州农业科学研究院实验数据验证模型的结构及动态.从对第1次及第2次施肥后植株吸氮量的模型模拟结果可以看出,杭州农业科学研究院与富阳的模拟结果数据都与实验数据相拟合,独立样本t检验结果为P>0.05=0.581及P>0.05=0.424.说明模型具有可应用性,但模型的拟合度与模型校准数据有很大相关,模型在具体应用上还有进一步改进的余地.

南京地区水稻田N素径流流失模拟模型

针对稻作水肥管理特点,建立了降雨-径流-N素流失模拟模型,根据实测与文献资料确定模型主要参数,并输入1951至2006年56a逐日降水资料运用自编程序进行计算机模拟运算,以分析南京地区降雨量与水田径流量及径流N流失量的关系。结果发现,除了降雨量和径流量影响径流N量以外,施肥日期及其与较强径流出现的时间间隔也对径流N量有很大影响。进一步分析表明,施肥后7d是降低水稻生长期径流N量的关键时期,6月中旬栽插有利于减少径流N的产生。

Assessing non-point source pollution in an apple-dominant basin and associated best fertilizer management based on SWAT modeling

Investigating the impact of apple-dominated areas on nitrogen(N)and phosphorus(P)losses at a basin scale was essential for the sustainable development of apple industry in China.This study conducted a survey on fertilizer application and built a Soil and Water Assessment Tool(SWAT)model to quantita-tively analyze the N and P losses in the Qixia apple-dominated area.Additionally,the decreases in N and P losses through adjusting the fertilizer application modes were evaluated.Results showed that average N and P losses in the Wulong River Basin(WRB)were 44.4 and 0.365 kg ha^(-1)in 2011-2017,respectively,and apple orchards accounted for 733%and 51.4%of the total N and P losses in the basin.Under nine fertilizer scheduling scenarios,three fertilizer schedule scenarios,automatic fertilizer application(S-AUTO),"one shot"mode(S1),and regulated fertilizer application(S-BSD),had the lowest N and P losses in apple orchards.The decreases in N loss ranged from 20.6%to 26.1%at the subbasin scale and 14.8%-30.7%at the basin outlet when applying the S-AUTO,S1,and S-BSD fertilizer application modes in Qixia apple orchards and all apple orchards in the WRB.The reductions in P loss varied from 22.0%to 46.1%at the subbasin scale and 14.6%-25.6%at the basin outlet.In orchard-dominated basin,N and P losses can be effectively reduced by optimizing the orchard fertilizer scheduling strategies.

生草减肥措施对坡地芒果园氮磷流失及养分吸收的影响

【目的】明确田间生草减肥管理措施对坡地芒果园氮(N)和磷(P)流失及养分吸收的影响,为有效防治坡地芒果园N和P流失协同养分增效提供科学依据。【方法】以广西百色市5年生热农坡地芒果园为研究对象,设生草减肥和常规管理2个处理,在自然降雨条件下测定2个处理坡地芒果园的径流产生量及泥沙、N和P流失量,同时分析芒果的N、P和钾(K)养分吸收量。【结果】研究区降雨主要集中在5—8月,中雨以上等级的降水量占观测期总降水量的77.28%。径流发生于连续中大降雨或单场降水量大于30.00 mm的降雨,且降水量与泥沙、总N和总P流失量呈极显著正相关(P<0.01)。连续中大降雨是泥沙及N和P流失的主要来源,其泥沙、N和P流失量分别占总泥沙、N和P流失量的74.23%~85.74%、73.70%~83.06%和77.88%~85.18%。生草减肥处理的总径流量、泥沙平均含量及总泥沙、总N和P流失量分别为476.2 m^(3)/hm^(2)、1.35 g/L、688.8 kg/hm^(2)、1014.7 g/hm^(2)和74.9 g/hm^(2),较常规管理处理分别减少66.20%、66.42%、88.68%、79.39%和83.51%。同时,生草减肥处理的偏生产力及N、P和K养分吸收量分别为19.3 kg/kg、108.9 g/株、16.4 g/株和151.8 g/株,较常规管理处理分别提高29.53%、8.68%、9.33%和8.98%。【结论】在广西百色市芒果产区坡地芒果园,地表径流发生于连续中大降雨或单场降雨大于30.00 mm的降雨,且与降水量呈极显著正相关,果园产流产沙量及N和P流失量受连续中大降雨的影响更明显。与常规管理相比,生草减肥措施可在有效减少地表径流及泥沙、N和P流失量的同时提高偏生产力及N、P和K养分的吸收量。