施肥与耕作对红壤坡地养分流失的影响

采用田间小区试验方法,通过田间实地监测,在自然降雨条件下,对南方典型红壤坡耕地采取不同施肥量及不同耕作方式对作物养分利用率及地表径流的影响进行了研究。结果表明,萝卜优化施肥（减氮增钾）和花生优化施肥（减氮增磷）,作物对氮磷养分吸收量均不会减少,同时提高了氮素养分利用率,萝卜提高15%,花生提高3.3%,优化施肥对磷素利用率没有影响且利用率较低,萝卜为8.55%～8.73%,花生为2.47%～2.63%。花生垄作氮肥利用率提高12.15%～12.77%,磷肥利用率提高1.24%～1.28%;同时期的径流量与降雨量呈显著正相关,相关系数达0.86;垄作使径流总量降低0.43×105L·hm-2,垄作＋秸秆覆盖比单纯垄作径流总量降低0.14×105L·hm-2;除对照（CK）外,径流水中TN、TP浓度处理间差异不显著,但可溶性养分（NO3--N、NH4＋-N、STP）后期有所不同,不同时期径流水中养分浓度变化较大,主要与施肥、农事活动及降水养分浓度有关;径流水氮磷养分流失总量与施肥量呈正比;旱地土壤氮素主要以泥沙结合态流失,NO3--N是可溶性无机氮流失的主要形态,占TN的10.53%～12.48%,NH4＋-N次之,占TN的6.19%～8.33%,磷素也以泥沙结合态流失为主,STP占TP的29.38%～40.74%。     

耕作措施对坡耕地红壤地表径流氮磷流失的影响

云南山地面积约占全省土地总面积的94%,特殊的地形特征,极易引发坡面土壤侵蚀和养分流失,严重影响了农业可持续生产。采取有效的农艺措施来减少坡耕地土壤养分流失是十分有必要的。为此,通过4年定位试验对顺坡(2组处理)、横坡(2组处理)2种耕作方向的复合农艺措施处理进行研究。结果表明:云南坡地红壤的径流时间主要集中在6—9月,且产流雨量占年降雨量的65.62%～75.82%。产流雨量与年降雨量呈现一致趋势。径流量和产流雨量呈线性关系(R_(NVF)~2=0.597 7,R_(OVF)~2=0.415 1,R_(OHF)~2=0.378 2,R_(OHFR)~2=0.335 5),其相关性大小顺序为顺坡处理横坡处理,不施肥处理施肥处理,覆膜处理揭膜处理(P0.01)。大雨(25～49.9 mm)和暴雨(≥50 mm)造成了年度大部分径流和养分的流失。横坡垄作组处理产生地表径流(177.13±28.87)～(182.28±33.75) mm,径流中总氮流失量(7.66±2.51)～(7.85±1.92) kg/hm~2,总磷流失量为(0.91±0.26)～(1.09±0.27) kg/hm~2,与顺坡垄作OVF(常规处理)相比径流和养分极显著减少了49.57%～52.13%,33.16%～53.88%(P0.01)。不同耕作措施下,复合耕作模式(优化施肥+横坡垄作+旺长期揭膜)拦截径流和养分流失的效果最好。RDA分析结果发现,与降雨量相比较,径流量是影响氮磷养分变化的主要环境因子(P0.01)。径流量与氮养分(NH_4~+-N除外)流失量的相关性高于与磷的相关性,表明氮比磷更容易随径流流失。顺坡处理NVF和OVF与环境因子径流量和氮磷养分流失量TN、TDN、NO_3~--N、NH_4~+-N、TP、TDP呈正相关,横坡处理OHF和OHFR与其呈负相关。     

保护性耕作和植物残体对土壤养分状况的影响

研究了不同耕作和秸秆还田方式对１年２熟（冬小麦－玉米）条件下壤质潮土养分含量的影响。结果表明，随着土壤耕翻程度的降低，土壤养分含量逐渐增加。免耕表土（０￣１０ｃｍ）有机质、全Ｎ和速效磷的含量显著（Ｐ〈０．０５）高于常规耕作（浅耕）方式，其速效钾含量也明显高于其他耕作方式，速效磷和速效钾的增加与免耕土壤有机质含量的提高以及由此导致的ｐＨ值下降显著相关，他们之间存在着显著（Ｐ〈０．０５）的线性关系；秸     

保护性耕作和植物残体对土壤养分状况的影响

研究了不同耕作和秸秆还田方式对1年2熟(冬小麦-玉米)条件下壤质湖土养分含量的影响。结果表明，随着土壤耕翻程度的降低，土壤养分含量逐渐增加。免耕表土(0～l0cm)有机质、全N和速效磷的含量显著(P<0．05）高于常规耕作(浅耕)方式，其速效钾含量也明显高于其他耕作方式，速效磷和速效钾的增加与免耕土壤有机质含量的提高以及由此导致的pH值下降显著相关，他们之间存在着显著(P<0．05)的线性关系；秸秆覆盖有利于表土养分的积累，但与其他秸秆还田方式积累养分量的差异未达到显著水平。     

油茶间作不同绿肥对土壤养分流失的影响

为有效防治油茶林水土流失和面源污染,在自然降雨条件下,采用径流小区定位观测法研究间作黑麦草、鼠茅草对油茶林土壤养分流失的影响。结果表明:(1)油茶间作黑麦草、鼠茅草可以提高土壤含水量与地表覆盖度,降低土壤容重,并显著提高表层土壤有机质及养分含量,增加土壤肥力。(2)4—7月油茶间作绿肥作物黑麦草、鼠茅草径流量分别减少18.5%~58.9%和17.9%~70.3%。(3)油茶间作鼠茅草系统减少径流养分流失的效果最佳,与对照组相比,地表径流中总氮、可溶性总氮、总磷、可溶性总磷、总钾、可溶性总钾的总流失量分别减少62.48%,56.17%,59.72%,57.97%,62.97%和61.76%;油茶间作黑麦草系统减少地表养分流失的效果较弱,与对照组相比,地表径流中总氮、可溶性总氮、总磷、可溶性总磷、总钾、可溶性总钾的总流失量分别减少30.95%,24.42%,25.03%,28.22%,32.97%和30.42%。各形态氮、磷、钾养分浓度较对照也有一定程度的降低。研究结果显示,油茶林间作绿肥,尤其是间作鼠茅草的水土保持效果显著。     

坡度对黄土坡面养分流失的影响实验研究

坡度是土壤养分流失的重要因素,通过室内人工降雨模拟试验,研究不同坡度土壤侵蚀和养分流失的过程与机制。研究结果表明:土壤中养分的流失量随坡度的增大而增大,但在20°附近时存在转折点,25°时养分流失量反而减小。同时利用两种类型描述径流养分浓度模型对实测资料进行分析,结果显示与指数函数模型相比较,采用幂函数模型能够较好地模拟黄土坡面非饱和条件下径流溶质浓度变化过程,同时幂函数模型也能够较好地描述径流中钾离子和溴离子的质量变化过程,为进一步完善黄土坡面径流养分迁移模拟模型提供了参考。     

三峡库区橘园种植绿肥对土壤养分流失的影响

在自然降雨条件下,采用径流小区法研究三峡库区橘园种植绿肥作物光叶苕子、白三叶和鼠茅草对土壤养分流失的影响。结果表明:与对照相比,橘园连续3a种植光叶苕子、白三叶和鼠茅草,其径流水总量分别减少11.0%,11.4%和24.0%;总氮流失量分别减少8.3%,16.7%和40.8%;总磷流失量分别减少7.5%,25.3%和58.0%;可溶性总氮流失量分别减少15.1%,28.0%和52.1%;可溶性总磷流失量分别减少24.3%,30.6%和53.8%;铵态氮流失量分别减少10.1%,23.7%和50.9%;硝态氮流失量分别减少21.9%,35.8%和55.1%。各形态的氮、磷养分浓度较对照也有一定程度的降低。橘园种植绿肥,尤其是种植鼠茅草,可有效地减少地表径流量以及地表径流水中的养分浓度,且二者共同作用,对养分流失量的减少效果更为明显。     

保护性耕作对土壤养分分布及冬小麦吸收与分配的影响

通过田间试验研究了华北平原山前平原区不同耕作方式下土壤氮、磷、钾等养分分布及冬小麦吸收与分配变化和对产量的影响。试验设深翻耕秸秆还田(MC)、秸秆还田旋耕(X)、秸秆粉碎免耕(NC)和整秸覆盖免耕(NW) 4 种冬小麦播前土壤耕作方式。试验结果表明, 6 年的不同耕作处理对土壤养分分布及冬小麦吸收与分配有显著影响。秸秆还田旋耕可显著提高土壤表层(0~5 cm)有机质、全氮以及碱解氮、速效磷、速效钾含量,但随土壤深度增加, 提高效果呈逐渐下降趋势; 20~30 cm 土层土壤有机质、全氮和速效氮含量显著低于秸秆粉碎免耕处理。两种免耕模式(NC、NW)植株的全氮、全磷、全钾含量在苗期明显低于翻耕(MC)和旋耕(X)模式,在返青期差异最为显著。到拔节和扬花期, 免耕(NC、NW)植株的全氮、全磷、全钾含量与翻耕(MC)和旋耕(X)之间的差异逐渐减少, 并最终影响到籽粒养分的积累。     

保护性耕作对地表径流及土壤侵蚀的影响

采用人工模拟降雨方法对陇中黄土高原连续实施5a的4种耕作措施：传统耕作（T），传统耕作结合秸秆还田（TS），免耕（NT），免耕加秸秆覆盖（NTS）下豌豆地收获后的径流起始时间、径流量、土壤侵蚀量进行了研究。结果表明，在降雨强度为85mm／h的条件下，NTS可以延缓径流，减小径流强度。与NT，TS，T这3种处理比较，NTS的径流量分别降低了2．4％，12．1％，34．7％。入渗量分别增加了2．7％，13．6％，38．6％。径流出现时间分别延迟1．17，0．83，3．83min。土壤侵蚀量减少了0．3％，17．7％，62．4％。可见，免耕秸秆覆盖的水土保持效应最为明显，传统耕作的方式极易发生土壤侵蚀。     

稻作区保护性耕作和小麦种植对土壤养分的影响

该文采用4个处理：常规犁耕-休闲(DTF)、常规犁耕-小麦(DTW)、保护耕作-休闲(CTF)和保护耕作-小麦(CTW),分析了10年后稻作区保护性耕作和小麦种植对土壤养分的影响。结果表明：在CTW处理下,土壤全N分别较DTF、DTW和CTF处理高10.03%、26.81%和23.17%。土壤碱解N也呈现相同的趋势;土壤全P,CTW处理下较DTF、DTW和CTF处理分别高12.93%、15.86%和21.36%。在0～10 cm土深,CTW处理下土壤有效P分别是DTF和DTW处理下的4.5和2.1倍;土壤全K在4种处理中与全N和P有类似的趋势;与处理DTF相比,Ca₂-P、Ca₈-P、Al-P、Fe-P、O-P和Ca₁₀-P在CTW下的含量迅速增加;代换态、易还原结合态、碳酸盐结合态、有机质结合态和无定形态Fe、Mn和Cu在CTW处理下含量降低,而残渣态Fe、Mn和Cu则增加。代换态和易还原锰结合态Zn在CTW处理下的含量增加,而相应地,无定形态和有机质结合态Zn则显著降低。而且,在有效Fe、Cu和Mn降低的同时,有效的Zn增加;稻作区,保护性耕作和小麦种植不仅增加表土层土壤养分的含量,而且可通过影响P、Fe、Mn、Zn和Cu的形态,缓解Fe和Mn对作物的毒害。     

水文条件对紫色土坡面土壤侵蚀及养分流失的影响

采用人工模拟降雨试验,研究水文条件对紫色土坡面土壤侵蚀及氮和磷养分流失的影响。试验处理包括2个施肥水平（低肥和高肥水平）,4个水文条件（自由下渗、土壤水分饱和、壤中流、壤中流＋降雨）和一个降雨强度（60 mm/h,历时60 min）。结果表明：壤中流＋降雨和土壤水分饱和条件下的土壤侵蚀量分别是自由下渗条件下的3.1和1.7倍,同自由下渗相比,壤中流、壤中流＋降雨和土壤水分饱和条件下,地表径流中NO3-N、HPO4-P的浓度和流失量有显著增加;低肥水平条件下,自由下渗、土壤水分饱和、壤中流和壤中流＋降雨地表径流中,NO3-N的浓度分别是0.88、58.90、698.41和87.80 mg/L,对应水文条件下地表径流中,HPO4-P的浓度分别是0.252、0.322、0.811和0.383 mg/L,高肥水平条件下,径流中的NO3-N和HPO4-P的浓度也有相同的趋势;土壤水分饱和条件下,地表径流中NO3-N和HPO4-P的流失量分别是自由下渗条件下的27～39和1.3倍,壤中流＋降雨条件下,地表径流中NO3-N和HPO4-P的流失量分别是自由下渗条件下的100～114和1.5～1.7倍,同时,壤中流＋降雨和土壤水分饱和条件下,泥沙中NO3-N和HPO4-P的流失量也比自由下渗条件下显著增加。     

Plant nutrient losses in runoff from conservation tillage corn

Conservation tillage in north Mississippi, U.S.A., reduced total (sum of solution and sediment) plant nutrient losses in runoff from corn, even though solution nitrogen (N) and phosphorus (P) concentrations in runoff were greater than from conventional-till and sediments were enriched severalfold in N and P. Plant nutrient losses were reduced by conservation tillage because of the significant reductions in soil loss. Soil losses from corn grown for grain were reduced more than 92% by reduced and no-till practices. Corresponding total losses of N and P were reduced about 70 and 80%, respectively.Conservation tillage reduced plant nutrient losses associated with sediments but increased solution P concentrations and losses in runoff. Solution P concentrations and losses, which were related to crop management, decreased in the following order: no-till corn (grain) ? no-till corn (silage) > reduced-till corn (grain) > conventional-till corn (grain) > conventional-till corn (silage). Solution P concentrations and losses in runoff increased with an increase in crop residues left on the soil surface after harvest and with a decrease in annual soil loss.     

多年固定道保护性耕作对土壤结构的影响

为了解决拖拉机作业机组作业时造成的土壤普遍压实,在10a连续固定道保护性耕作试验基础上,研究了固定道保护性耕作对土壤容重、孔隙度、紧实度、水分以及冬小麦产量的影响。试验结果表明,对于作物生长带,固定道保护性耕作可以降低0～20cm土层的容重6.8%,提高0～40cm土层土壤总孔隙度4.6%,降低0～30cm土层土壤紧实度31.5%,提高0～1m土层蓄水能力,在固定道占地20%的情况下,仍能提高冬小麦产量10.8%。因此,固定道保护性耕作是减少土壤压实、改善土壤结构、提高小麦产量的有效耕作方式。     

稻-油轮作下保护性耕作对土壤肥力的影响及评价

本文选取湖北省武穴市、荆州市和武汉市3个稻-油轮作长期定位试验点(试验时间分别为9年、5年和3年),通过连续监测土壤容重、孔隙度、p H、有机质、全氮、全钾、碱解氮、速效磷和速效钾等,研究在不同耕作年限和方式下,秸秆还田和免耕对水稻季(2015年10月)和油菜季(2016年5月)各土层(0~20 cm和20~40 cm)中土壤物理性质和养分的影响,并应用内梅罗指数法综合评价各土层土壤肥力水平,以探讨长期秸秆还田对土壤肥力的影响。结果表明:1)秸秆还田处理使水稻季和油菜季的土壤容重降低2.00%~16.54%,土壤总孔隙度增加1.00%~15.07%;而免耕处理下油菜季的变化与其相反,水稻季的变化不显著。2)秸秆还田处理增加了3个试验点0~20 cm土层中有机质(4.76%~35.07%)、全氮(1.80%~32.03%)、速效磷(20.95%~65.82%)、碱解氮(5.97%~37.00%)和速效钾(8.71%~133.04%)的含量,其中速效钾含量的增加幅度最高;免耕处理对土壤各养分的影响不显著,而在配施秸秆后,相对于其他处理,其对各养分的增加效果相对最好。各处理对20~40cm土层的影响与0~20 cm土层相似,但整体增加效果没有后者显著。3)各试验处理中,免耕+秸秆还田和施氮磷钾肥+秸秆还田两种处理增加各土层土壤综合肥力系数较大(7.56%~25.93%),它们对土壤肥力的提高效果相对较好。     

Relationship between soil structure and runoff/soil loss after 24 years of conservation tillage

A better understanding of tillage and stubble management effects on surface soil structure is vital for the development of effective soil conservation practices for the long-term. Relationships between aspects of soil structure and runoff/soil loss were investigated in 24 year old field experiment on an Oxic Paleustalf, in NSW, Australia. Two tillage/stubble management systems were compared, namely direct drilled/stubble retained (DD/SR) versus conventional tillage/stubble burnt (CC/SB). Tillage and stubble burning significantly increased bulk density and decreased the macro-aggregate stability, mean weight diameter (MWD), geometric mean diameter (GMD) and total porosity, particularly macroporosity (>60 μm). For the 0–5 cm layer, DD/SR had significantly higher water stability of macro-aggregates >2 mm than CC/SB (165 g/kg versus 78 g/kg), and the volume of pore space of diameter >60 μm at 0–5 cm depth was significantly greater (more than 11%) for DD/SR than for CC/SB. Under simulated rainfall (100 mm/h) and the removal of surface stubble, both runoff and soil loss were significantly higher under CC/SB compared to DD/SR. The infiltration rate at the end of the experiment under DD/SR was 3.7 times that of CC/SB (85 mm/h versus 23 mm/h). There were significant correlations between the proportion of soil particles >0.25 mm measured after wetting by rain and both final infiltration rate (P < 0.001) and soil loss (P < 0.001). It was concluded that 24 years of direct drilling and stubble retained practices significantly reduced runoff and soil erosion hazards, due to a fundamental change in soil structure, viz. higher soil aggregate stability and higher macroporosity of the surface soil.     

Long-term conservation tillage results in a more balanced soil microbiological activity and higher nutrient supply capacity

Soil health depletion due to intensive tillage operations is a global issue in the agricultural sector. Conservation tillage (CT) which involves non-inversion tillage and leaving ∼30% of the soil surface covered with crop residues, is a strategy designed to enhance soil health. However, no comprehensive study to investigate the long-term effect of CT on soil biological activity and the soil nutrient supply has yet been widely carried out. Biological and chemical soil properties were assessed at depths 0–5, 10–15, and 20–25 cm depths after 18 years of CT and conventional tillage practice (PT). Various stages in the vegetative growth of maize were investigated in 2021 in Hungary. The findings indicated that tillage intensity, soil depth, and growth stages all significantly influenced soil enzyme activities and the concentration of soil nutrients. Less soil disturbance resulted in a significantly larger concentration of soil carbon parameters (total organic carbon and labile carbon) in CT plots, where the activity of β-glucosidase and dehydrogenase (DHA) in the upper soil layer increased significantly (0.7–2.6 and 2.6–4.7 times, respectively) compared to PT. The high amount of organic matter and the greater resistance to erosion observed in CT also contributed to the higher concentration of available nutrients (NH₄, NO₃, Ca, K) and total P in the surface soil layer. Phosphatase activity was highest in the mid-stage of vegetative growth and was positively correlated to the total P concentration. The alterations in soil water content were clearly negatively correlated with the change in DHA and phosphatase activity. Overall, due to the more balanced environmental conditions, the decomposition of organic substances was more balanced and slower in CT than in PT. This implied that the mobilization of nutrients in the soil was more balanced as well, and that the nutrients were released gradually. The enhancement of the soil nutrient-supplying capacity achieved by means of long-term conservation tillage provides a promising strategy for sustainable nutrient management.     

保护性耕作对土壤风蚀的影响

保护性耕作能够有效减少农田土壤风蚀.通过室内风洞模拟试验,研究秸秆覆盖、留茬和垄作3种保护性耕作措施对黄土高原北部农田土壤风蚀的影响.结果表明:1)秸秆覆盖和留茬能有效降低土壤风蚀速率,秸秆覆盖量为4 210 kg/hm2时土壤风蚀速率最小,与对照相比减少62.8%;垄作在低风速下能够降低土壤风蚀率,垄向与风向垂直时降...     

施肥对菜园土壤养分淋溶流失浓度的影响

利用盆栽种植空心菜和菜心并收集测定土壤渗漏水氮磷钾养分浓度,研究了不同施肥水平对土壤氮磷钾淋溶流失浓度的影响。试验表明,在较大施肥量或化肥当季损失量范围内,土壤渗漏水硝态氮、总磷和钾浓度与氮、磷、钾施肥量或损失量之间呈非线性关系,但在中低施肥量时则表现为线性关系。化肥当季损失量与土壤渗漏水养分浓度呈显著水平的线性正相关,由此提出“双速率转折点”概念用以评价土壤养分流失潜力。当施肥量或化肥当季损失量超过双速率转折点X0后,土壤淋溶排水养分浓度将以非线性形式急剧增加。因此,从环保角度看,施肥量不应超过X0。盆栽试验表明,以化肥当季损失量为基础的灰泥土、灰黄泥土和黄泥土的氮肥X0分别为每盆N 0.35、0.32和0.34 g,磷肥X0分别为每盆P 0.06、0.06和0.09 g,灰泥土和灰黄泥土的钾肥X0则分别为K 0.17和0.18 g;与土壤渗漏水养分浓度为基础所确定的氮、磷、钾X0有显著水平的线性正相关。以环保为目标的氮磷钾用量X0大多数低于以产量为目标的经济施肥量。化肥当季损失量参数较易获得,可作为环保施肥的依据。     

Effect of long-term conservation tillage on soil biochemical properties in Mediterranean Spanish areas

In semi-arid Mediterranean areas, studies of the performance of conservation tillage systems have largely demonstrated advantages in crop yield, soil water storage and soil protection against wind and water erosion. However, little attention has been given to interactions between soil biochemical properties under different tillage practices. Biochemical properties are useful tools to assess changes caused by different soil tillage systems in long-term field experiments. This study deals with the effect of long-term tillage practices (reduced tillage and no-tillage vs. traditional tillage) on soil chemical properties and microbial functions in three different sites of Spain (two of them located in the Northeast and one in the Southwest) under semi-arid Mediterranean conditions. Soil biological status, as index of soil quality, was evaluated by measuring microbial biomass carbon (MBC) and dehydrogenase (an oxidoreductase) and protease (a hydrolase) activities at three soil depths (0–5, 5–10 and 10–25 cm). In the three experimental areas, increases in soil organic matter content, MBC and enzymatic activities were found at the superficial layers of soil under conservation tillage (reduced tillage and no-tillage) in comparison with traditional tillage. Values of the stratification ratio of some biochemical properties were significantly correlated with yield production in Northeast sites.Conservation tillage has proven to be an effective strategy to improve soil quality and fertility in Mediterranean areas of Spain.