粪肥添加明矾对降低农田磷和重金属流失的作用

施用粪肥引起农田氮、磷流失的增加已引起人们广泛的关注。为了解粪肥中添加明矾可否降低农田污染物的流失,采用化学分析与田间试验相结合的方法研究了添加明矾对粪肥中水溶性养分和重金属浓度及施粪肥后农田养分、重金属流失的影响。结果表明,粪肥中添加明矾可大大降低其中的水溶性P和重金属浓度,其中水溶性P的下降幅度达79.3%。添加明矾后,粪肥施入农田形成的径流中P和重金属浓度明显低于不添加明矾的处理。但添加明矾对农田可溶性总N、NO3-N和NH4-N流失的影响不大。粪肥中添加明矾不会引起地表径流中铝浓度明显增加,对蔬菜产量影响不明显。     

农业系统中磷的输移及利用

土壤磷对作物生长及水质污染有重要影响,农业生产中施入过量的磷会引起水体的富营养及水质下降。美国土壤学家N.C.Hansen等通过分析土壤及水中磷的形态、磷的管理、磷的吸附过程,认为土壤中可溶性磷是通过地表径流、壤中流及深层淋溶输移到水中。连续数十年施过量磷肥导致土壤磷浓度升高,将其降到正常水平需很长时间。水土流失是土壤磷流失的主要途径。为了减少土壤中磷的流失及保护水质,在农业生产中,采取水保耕作措施可有效防止磷的流失。减少耕作次数可降低径流中磷的浓度,在高寒易发生冻融侵蚀的地区,适当增加耕作次数可减少土壤磷的流失;穴状、条带状或结合播种施肥、保留植被盖度是农业管理中减少磷输移的有效方法。     

美国有关可溶性磷的流失评价模型

农田中磷的流失是一个地区发生非点源污染的主要原因 ,靠传统水保措施不能有效地控制磷的污染。美国学者M T Walter依据现实可靠的信息 ,通过一个简单的模型对有机肥施用措施进行了评价 ,并预测可溶性磷在常年地表径流中的流失情况。研究表明 :在短期内 ,由于土壤中磷的蓄积和畜牧生产 ,可溶性磷流失到径流中的概率是 5 0 % ;而遵循水质敏感区理论的施肥措施能使可溶性磷的流失下降到 2 5 %。施肥时间和不同的施肥措施对可溶性磷的流失影响显著。     

施用鸡粪土壤中磷的径流损失特征研究

研究了施用鸡粪土壤中磷养分在自然降雨过程中随地表径流流失的变化规律.结果表明:颗粒附着态磷(PP)占总磷(TP)的61.1%～79.5%,是土壤中磷索在自然降雨过程中随地表径流流失的主要形态.基于作物需磷量计算鸡粪用置较基于作物需氮量能有效降低地表径流中不同形态磷浓度,其中TP降幅为8.0%～46.3%.PP降幅为6.0%～48.2%.TDP降幅为15.1%～46.0%,DIP降幅为29.4%～55.5%.表明基于作物需磷量计算鸡粪施用量能有效降低土壤中磷索在自然降雨过程中随地表径流的流失风险.添加沸石或铁盐可有效降低地表径流中TP和PP浓度,从而有效降低磷随地表径流损失的风险.     

水稻田磷素径流流失形态变化特征的模拟研究

通过对一系列含有不同磷水平的原状土室内模拟磷素流失的方法,在同一降雨强度下,分别研究了不施用磷肥时不同磷含量的土壤径流磷流失和施用磷肥24 h后的径流磷流失量,以及区分土壤本身不同水平的残余磷和新施入的肥料磷对径流流失磷的贡献。结果表明:在所有处理中,施肥量、土壤残余磷与总磷流失均呈正相关关系;溶解反应磷(DRP)是总溶解磷(TDP)的主要成分,而TDP占总磷(TP)的60%以上,是流失磷的主要形态,溶解性难反应态磷(DUP)只占流失总磷的1.2%~4.6%,但实际浓度在OP2有机处理中达到0.28 mg/L,这部分磷不易下沉,特别是施肥后短期内的降雨径流,可能导致DUP流失量大大增加。与不施肥试验相比,施入无机肥后,DRP、TDP量均显著增加,所占流失总磷的相对比例也明显增加,相对应的TPP、DUP占总流失磷的相对比例则依次减少;而与无机肥处理相比,有机肥处理的OP1、OP2变化则不同,DUP占TP的相对比例显著增加,达到4.4%和4.6%,但其它形态磷所占相对比例则略有减少。此外,线性回归分析表明了土壤新施入的磷肥是流失负荷中磷的主要来源。     

玉米间种绿肥作物对径流中磷含量的影响

土壤中磷的流失可导致水体富营养化。农业最佳管理措施是通过减少土壤侵蚀来减少磷的流失。美国土壤学家K le inm an等人利用人工模拟降雨研究玉米间种或混合紫花苜蓿等绿肥作物在施肥后对径流中可溶性磷质量浓度的影响程度。其结论是:绿肥作物增加了小区的植被盖度,可防止土壤溅蚀;不同绿肥作物径流量差异不显著。坡位对径流也有影响。绿肥作物可减少泥沙输出。施肥前,绿肥作物对可溶性磷流失没有影响。施肥后,因有机肥中含有可溶性磷,可提高径流中可溶性磷质量浓度,导致施肥后磷流失量增大。施肥量与磷的流失量密切相关,因此,应控制施肥量以减少磷的流失。     

施用磷肥对土壤磷层化和水质的影响

免耕会导致耕地中磷(P)层化,进而促使农田可溶性磷(SP)的流失,导致富营养化。为减少土壤磷流失,提出玉米—大豆轮作区减少土壤磷层化和径流磷流失的施肥策略。实验共设立未施肥、施用磷酸二铵(DAP)、施用磷酸一铵(MAP)、地表施肥(干性肥料或液体肥料)两种施肥方式、注入肥料(干性肥料或液体肥料)、耕作施肥以及覆盖作物措施9个实验样地。隔年施肥量为24.4 kg/hm~2,逐年施肥量为9.6 kg/hm~2。翻地与其他处理相比,在0～5 cm表土层中可溶性磷含量更高。在降雨实验中,肥料来源和施肥量对径流中的总磷量和可溶性磷量影响不大。实验中可溶性磷浓度最高的地块为隔年施磷酸二铵的实施覆盖作物措施的样地。注入肥料施肥法在降低土壤可溶性磷的流失的同时加剧了土壤侵蚀及总磷的流失。耕种时注入液体肥料(聚磷酸盐)的样地损失的总磷量和可溶性磷量比地表施肥的样地低。     

施肥对北京山区农田地表氮磷流失的影响——以密云水库流域为例

农田非点源污染是最普遍的非点源污染类型之一,直接威胁北京市密云水库的水质状况;施用化肥是农田非点源污染物的主要来源.以北京市山区的农田化肥施用现状为基础,紧邻密云水库布设径流试验小区,种植当地的主要作物——夏玉米,设置常规(施肥)和对照(不施肥)2种处理,分析天然降雨条件下,施肥对农田地表氮和磷流失的影响.结果表明:施肥显著提高地表径流中氨态氮的浓度,但对径流硝态氮、总氮、可溶磷和总磷的影响有限;附着于泥沙上的颗粒态磷质量分数因施肥显著增加,但颗粒态氮质量分数仅在底肥施用后的首次产流中,表现出较大差异;泥沙是地表径流中氮和磷流失的主要载体,试验期间常规和对照小区,氮随泥沙流失负荷分别占氮流失总量的58.6％和53.6％,磷随泥沙流失负荷占比分别为97.2％和96.5％.研究结果可为密云水库流域农业生产管理和非点源污染治理提供参考.     

改良剂降低富磷蔬菜地土壤磷和氮流失的作用

为了解不同改良剂对土壤中磷和氮的稳定作用,进行田间试验研究在施用量为2.5t/hm2时氢氧化铝、石灰石粉、石膏、氯化钙和粉煤灰5种改良剂对蔬菜地地表径流中磷和氮浓度的影响。结果表明,改良剂施用可明显降低土壤有效磷和水溶性磷含量,轻微增加土壤中NH4+-N含量,但对土壤中NO3--N影响不大。施用改良剂可显著降低蔬菜地地表径流中总磷、溶解态磷、颗粒态磷和NH4+-N的浓度,增加水溶性有机氮浓度,但对水溶性总氮和NO3--N浓度影响不明显。与对照比较,施用氢氧化铝、石灰石粉、石膏、氯化钙和粉煤灰5种改良剂的地表径流中总磷浓度下降比例平均分别为13.68%,35.54%,38.72%,43.77%和45.02%,溶解态磷浓度下降比例平均分别为16.05%,32.42%,48.75%,55.38%和38.98%;NH4+-N浓度下降比例平均分别为24.21%,37.84%,11.31%,10.08%和55.56%。总体上,施用氯化钙和粉煤灰降低地表径流中磷浓度的效果好于其他改良剂。     

长期施肥下黄壤旱地磷对水环境的影响及其风险评价

通过对贵州中部黄壤旱坡地进行采样以及采用无界径流小区法收集地表径流样品 ,探讨长期施肥下旱地磷素水平与地表径流磷浓度的变化及其对水环境的影响。结果表明 :长期施肥下黄壤旱地的磷素水平不断提高 ,CaCl2 浸提磷 (溶解态活性磷 )和NaOH浸提磷 (藻类可利用的土壤总磷 )与土壤全磷或有效磷之间存在显著的相关性 ,土壤富磷化的同时 ,旱地磷对水环境影响的潜能明显提高。黄壤旱坡地中CaCl2 浸提磷、Olsen P、NaOH浸提磷、土壤磷吸持指数、土壤磷饱和度与地表径流中颗粒态磷、生物有效性磷和溶解态活性磷之间的相关性均达显著水平 ,以这些参数作为评价指标 ,初步将黄壤旱地磷对水环境的潜在影响程度分为 3个等级     

蔬菜地土壤磷饱和度及其对磷释放和水质的影响

为了解蔬菜地土壤磷素的积累对水环境的影响,我们在浙江省选择了33个代表性蔬菜地,采集和分析了土壤、地表水和地下水样的磷素状况,从土壤磷饱和度的角度,研究了浙江省主要蔬菜土壤磷积累状况及其对地表和地下水水质和土壤磷释放潜力的影响。结果表明,半透膜渗析法测得的磷释放量与土壤磷积累呈正相关,磷释放量随土壤磷饱和度的提高而增加。蔬菜地土壤磷饱和度的增加可显著提高地表水体和地下水中磷的浓度,当土壤磷饱和度小于25%左右时,水体中磷浓度随土壤磷饱和度增加较为缓慢;但当磷饱和度大于25%时,水体中磷浓度随土壤磷饱和度提高迅速上升。地表水中磷浓度主要与表层土壤磷饱和度有关;地下水中磷浓度主要受深层土壤磷饱和度的影响,与表层土壤磷饱和度的相关性较小。土壤磷饱和度可很好地表征土壤磷释放和对环境的潜在影响。     

有机肥施用对水田土壤溶液氮磷动态变化及环境的潜在影响

通过原状土柱模拟试验,开展了稻麦轮作条件下,有机肥施用对水稻田面水及渗漏水中N、P变化规律影响的研宄.结果表明,水稻施肥后的一定时期内田面水中可溶性总N(DTN)、NH_4~+-NO_3~--N与N肥施用量呈正相关,伴随着3次施肥呈现出3个峰值,田面水中DTN以NH_4~+-N为主.80 cm深处渗漏水的DTN、NH_4~+-N、NO_3~--N浓度均是施肥处理高于对照,但各处理间没有显示与施肥量的相关性.田面水中溶解性总P(DTP)在整个生育期内与猪粪用量呈显著正相关,当猪粪用量超过鲜重40 t/hm~2时,渗漏液中DTP含量显著高于其他处理.说明过量有机肥施入土壤后,P素不能被作物立即吸收,也不易被土壤固定,随渗漏液进入地下水,成为水体富营养化的诱因.     

不同用量猪粪对红壤花生坡地水土流失和磷素流失的影响

通过田间径流微区定位试验,以中亚热带3种典型母质(花岗岩、红砂岩、红黏土)发育红壤花生坡地为研究对象,以当地常规化肥用量处理为对照,连续3年研究了在常规化肥用量减半条件下配施6个不同用量腐熟猪粪(猪粪含有0,0.5,1,2,4,8倍的对照处理磷用量)对红壤花生坡地水土流失和磷素流失的影响,以期为典型红壤地区合理施用猪粪提供科学依据。结果表明:化肥减半配施猪粪处理能有效降低红壤坡地的产流产沙,但随着猪粪用量的增加,径流水和泥沙磷含量均呈线性增加,环境风险增大。径流量和泥沙量均为花岗岩红壤红砂岩红壤红黏土红壤。配施3 500kg/(hm~2·a)猪粪,花岗岩红壤的径流量减少了28.0%、泥沙量减少了6.3%,红砂岩红壤的径流量减少了23.2%、泥沙量减少了37.1%;而配施7 000kg/(hm~2·a)猪粪,红黏土红壤的径流量减少了40.7%,泥沙量减少了12.8%。当花岗岩红壤、红砂岩红壤、红黏土红壤的猪粪用量分别达到14 000,28 000,28 000kg/(hm~2·a)时,径流水总磷平均含量超过地表水环境质量标准V类限值。径流水总磷含量为花岗岩红壤红黏土红壤红砂岩红壤,而泥沙总磷含量则为红黏土红壤花岗岩红壤红砂岩红壤。在减半化肥用量条件下花岗岩红壤和红砂岩红壤配施与常规化肥处理等磷量[P含量40kg/(hm~2·a)]的猪粪、红黏土红壤配施2倍常规化肥处理磷含量[P含量80kg/(hm~2·a)]的猪粪,可有效减少水土流失,且3年内不会增加磷素流失风险。     

不同有机废弃物对土壤磷吸附能力及有效性的影响

城郊农地是循环有机废弃物的重要场所,但长期施用畜禽粪和城市污泥可引起土壤磷素积累、磷饱和度提高,增加土壤向环境流失磷的风险。为了解施用不同来源的有机废弃物对城郊耕地土壤磷素化学行为的影响,选择4种不同磷含量的土壤,探讨在等量磷素情况下,施用KH2PO4、猪粪/稻草秸秆堆肥、沼渣、猪粪、鸡粪、生活垃圾堆肥和2种污泥等不同磷源时,土壤有效磷含量及磷吸附能力的差异。结果表明,施用有机废弃物增加了土壤有效磷和水溶性磷含量,降低了土壤对磷的吸附能力,但影响程度因有机废弃物来源而异。施用猪粪/稻草秸秆堆肥和猪粪降低土壤磷最大吸附量比例(9.03%~15.60%)与施KH2PO4(10.59%~16.63%)相当,但施用沼渣、鸡粪和生活垃圾堆肥降低土壤磷最大吸附量的比例(5.09%~9.84%)明显低于施KH2PO4;施用2种污泥降低土壤磷最大吸附量的比例(4.32%~6.77%)最小。不同有机废弃物对土壤有效磷的影响差异较小,但对水溶性磷的影响较大。施用有机废弃物后,土壤磷最大吸附量的下降值与施用有机废弃物中铁、铝、钙含量呈负相关;土壤水溶性磷的变化量与施用有机废弃物后土壤交换性钙的增加量呈负相关,表明有机废弃物中铁、铝和钙等矿质成分的增加,可在一定程度上减少有机废弃物在土壤循环处理时磷对环境的负影响。在农田施用有机废弃物时,不仅要考虑有机废弃物磷素状况,也应适当考虑其他矿质成分的组成特点。该研究可为城郊农地科学施用有机废弃物提供依据。     

Erosion rates and nutrient losses affected by composted cattle manure application in vineyard soils of NE Spain

Land preparation for mechanisation in vineyards of the Anoia–Alt Penedès region, NE Spain, has required major soil movements, which has enormous environmental implications not only due to changes in the landscape morphology but also due to soil degradation. The resulting cultivated soils are very poor in organic matter and highly susceptible to erosion, which reduces the possibilities of water intake as most of the rain is lost as runoff. In order to improve soil conditions, the application of organic wastes has been generalised in the area, not only before plantation but also every 3–4 years at rates of 30–50 Mg ha^− 1 mixed in the upper 30 cm.These organic materials are important sources of nutrients (N and P) and other elements, which could reduce further fertilisation cost. However, due to the high susceptibility to sealing of these soils, erosion rates are relatively high, so a higher nutrient concentration on the soil surface increases non-point pollution sources due to runoff.The aim of this study is to analyse the influence of applied composted cattle manure on infiltration, runoff and soil losses and on nutrients transported by runoff in vineyards of the Alt Penedès–Anoia region, NE Spain. In the two plots selected for the analysis, composted cattle manure had been applied in alternate rows 1 year previous to the study. In each plot soil surface samples (0–25 cm) were taken and compared to those of plots without manure application. The study was carried out at laboratory scale using simulated rainfall. Infiltration rates were calculated from the difference between rainfall intensity and runoff rates, and the sediment and total nitrogen and phosphorus were measured for each simulation. In addition, the influence of compost was investigated in the field under natural rainfall conditions by analysing the nutrient concentration in runoff samples collected in the field (in the same plots) after seven rainfall events, which amount different total precipitation and had different erosive character.Compost application increases infiltration rates by up to 26% and also increases the time when runoff starts. Sediment concentration in runoff was lower in treated (13.4 on average mg L^− 1) than in untreated soils (ranging from 16.8 to 23.4 mg L^− 1). However, the higher nutrient concentration in soils produces a higher mobilisation of N (7–17 mg L^− 1 in untreated soils and 20–26 mg L^− 1 in treated soils) and P (6–7 mg L^− 1 in untreated soils and 13–19 mg L^− 1 in treated soils). A major part of the P mobilised was attached to soil particles (about 90% on average) and only 10% was dissolved. Under natural conditions, higher nutrient concentrations were always recorded in treated vs. untreated soils in both plots, and the total amount of N and P mobilised by runoff was higher in treated soils, although without significant differences. Nutrient concentrations in runoff depend on rainfall erosivity but the average value in treated soils was twice that in untreated soils for both plots.     

Erosion rates and nutrient losses affected by composted cattle manure application in vineyard soils of NE Spain

Land preparation for mechanisation in vineyards of the Anoia–Alt Penedès region, NE Spain, has required major soil movements, which has enormous environmental implications not only due to changes in the landscape morphology but also due to soil degradation. The resulting cultivated soils are very poor in organic matter and highly susceptible to erosion, which reduces the possibilities of water intake as most of the rain is lost as runoff. In order to improve soil conditions, the application of organic wastes has been generalised in the area, not only before plantation but also every 3–4 years at rates of 30–50 Mg ha^− 1 mixed in the upper 30 cm.These organic materials are important sources of nutrients (N and P) and other elements, which could reduce further fertilisation cost. However, due to the high susceptibility to sealing of these soils, erosion rates are relatively high, so a higher nutrient concentration on the soil surface increases non-point pollution sources due to runoff.The aim of this study is to analyse the influence of applied composted cattle manure on infiltration, runoff and soil losses and on nutrients transported by runoff in vineyards of the Alt Penedès–Anoia region, NE Spain. In the two plots selected for the analysis, composted cattle manure had been applied in alternate rows 1 year previous to the study. In each plot soil surface samples (0–25 cm) were taken and compared to those of plots without manure application. The study was carried out at laboratory scale using simulated rainfall. Infiltration rates were calculated from the difference between rainfall intensity and runoff rates, and the sediment and total nitrogen and phosphorus were measured for each simulation. In addition, the influence of compost was investigated in the field under natural rainfall conditions by analysing the nutrient concentration in runoff samples collected in the field (in the same plots) after seven rainfall events, which amount different total precipitation and had different erosive character.Compost application increases infiltration rates by up to 26% and also increases the time when runoff starts. Sediment concentration in runoff was lower in treated (13.4 on average mg L^− 1) than in untreated soils (ranging from 16.8 to 23.4 mg L^− 1). However, the higher nutrient concentration in soils produces a higher mobilisation of N (7–17 mg L^− 1 in untreated soils and 20–26 mg L^− 1 in treated soils) and P (6–7 mg L^− 1 in untreated soils and 13–19 mg L^− 1 in treated soils). A major part of the P mobilised was attached to soil particles (about 90% on average) and only 10% was dissolved. Under natural conditions, higher nutrient concentrations were always recorded in treated vs. untreated soils in both plots, and the total amount of N and P mobilised by runoff was higher in treated soils, although without significant differences. Nutrient concentrations in runoff depend on rainfall erosivity but the average value in treated soils was twice that in untreated soils for both plots.     

Composts Vary in Their Effect on Soil P Pools and P Uptake by Wheat

With diminishing world reserves of phosphorus (P) deposits and rising fertilizer prices, it is important to find alternate sources of P for crops. The aim of this research was to evaluate the effect of four different composts C1 (animal manure and straw), C2 (garden waste), C3 (wood chips and bark), and C4 (kitchen waste) on soil P pools and P uptake by wheat on 14, 28, and 72 days after compost application. The composts were applied as a 2.5 cm thick layer on the soil surface. During sampling, only the soil underlying compost was sampled. Soil pH and total organic carbon were not affected by the amendments. Soil respiration was significantly higher in compost-amended soils compared with the unamended soil except with C4 on day 72. Addition of composts increased plant growth, and P uptake being highest on day 72 with C1 and C4. With little effect on available P concentration on day 14, there was a conversion of organic P into inorganic P in the compost treatments suggesting net mineralization of organic P on day 28. On day 72, the concentrations of the less labile P forms were higher in the compost treatments compared with the unamended suggesting precipitation and fixation as well as synthesis of organic P. This study showed that mulching with composts having high available and total P concentrations can provide plants with P and also increase soil P concentrations which could reduce the fertilizer requirement for the following crop.     

长期施磷稻田土壤磷素累积及其潜在环境风险

应用常规化学分析法和数学统计方法,基于太湖地区13年的长期定位试验,研究长期不同施磷水平下[0(不施磷)、30 kg.hm 2.a 1(低磷)、60 kg.hm 2.a 1(适磷)、90 kg.hm 2.a 1(高磷)]稻麦轮作系统稻田土壤磷素累积规律及磷素流失引发的环境风险。在本试验区土壤环境条件下,可能发生稻田磷素淋溶及径流的土壤耕层(0~15 cm)Olsen-P临界值分别为26.0 mg.kg 1和24.8 mg.kg 1。连续13年适磷、高磷施肥,土壤耕层Olsen-P含量分别达到26.9 mg.kg 1和33.2 mg.kg 1,均高于临界值浓度,且已导致稻田田面水与30 cm渗漏水中总磷浓度显著升高,大大提高了稻田磷素淋溶及径流的风险。低磷施肥土壤Olsen-P长期稳定在(10.1±2.0)mg.kg 1水平,并且每年的稻麦产量与高磷、适磷处理相比并无显著差异,而长期低磷施肥土壤磷的流失风险也较小。因此,在太湖地区稻麦轮作体系下,磷肥不宜以常规适磷水平长期施用,建议以低磷水平(30 kg.hm 2.a 1)长期施用或以适磷水平(60 kg.hm 2.a 1)间歇式施用。     

稻田系统管理措施对微生物生物量C、N、P的长期影响

A 12-year field experiment was conducted to investigate the effect of different tillage methods and fertil-ization systems on microbial biomass C,N and P of a gray fluvo-aguic soil in rice-based cropping system .Five fertilization treatments were designed under conventional tillae(CT) or on tillage(NT) system:no fertilizer(CK) ; chemical fertilizer only(CF) ; combining chemical fertilizer with pig manure(PM); combining chemical fertilizer with crop straw (CS) and fallow (F). The results showed that biomass C,N and P were enriched in the surface layer of no-tilled soil,whereas they distributed relatively evenly in the tilled soil,which might result from enrichment of crop resdue,organic manure and mineral fertilzer,and surficial developent of root systems under NT.Under the cultivation system NT had slightly greater biomass C,N and P at 0-5 cm depth ,significantly less biomass C,N and P at 5-15 cm depth ,less microbial biomass C,N and equivalent biomass P at 15-30 cm depth as compared to CT,indicating hat tillage was beneficial for the multiplication of organims in the plowed layer of soil.Under the fallow system,biomass C,N and P in the surface layer were significantly greater for NT than CT while their differences between the two tillage methods were neligible in the deeper layers.In the surface layer,biomass C,N and P in the soils amended with oranic manure combined with mineral fertilizers were significantly greater than those of the treatments only with mineral fertilizers and the control.Soils without fertilzer had the least biomass nutrient contents among the five fertilization treatments.Obviously,the long-term application of organic manure could maintain the higher activity of microorganisms in soils.The amounts of biomass C,N and P in the fallowed soils varied with the tillage methods;they were much greater under NT than under CT,especially in the surface layer,suggesting that the frequent plowing could decrease the content of organic matter in the surface layer of the fallowed soil.     

砂质土壤磷素的组成特点与释放规律研究

砂质土壤磷素主要以可提取态形式积累,有很高的释放潜力。该类土壤磷素的释放受土壤pH、土水作用时间和土壤溶液化学组成等的影响。土壤酸化、土壤溶液中Na+浓度的提高及土壤与水的作用时间增加可促进土壤磷素的释放。用淋洗方法和平衡提取等2种方法对土壤磷素的释放评价表明,淋洗方法测得的P量较小,可代表土壤短期内P释放强度;而平衡提取法提取的P数量较大,可代表土壤P长期释放的容量。