科尔沁沙地固定沙丘土壤氮素空间分布特征研究

为了研究固定沙丘土壤N素空间分布特征,选择以栽植小叶锦鸡儿25年后的固定沙丘为研究对象,从迎风坡、顶坡和背风坡3个位置4个层次(0～5、5～10、10～20和20～40 cm)进行取样分析.研究结果表明:全N、NO_3~--N和NH_4~+-N含量均随着土层加深而呈现出减少的趋势,0～5 cm土层显著高于其他各层.表层土壤受凋落物的影响较大,从而相对于深层土壤来说积累了更多的N素.全N、NO_3~--N和NH_4~+-N含量在不同坡位间存在显著差异(p＜0.01):全N和NO_3~--N含量在迎风坡较高,而NH_4~+-N含量在背风坡较高.丛下全N、NO_3~--N和NH_4~+-N的含量显著高于丛间(p＜0.01).土壤电导率与全N、NO_3~--N、NH_4~+-N含量呈显著正相关,而pH与NO_3~--N、NH_4~+-N含量呈显著负相关,NO_3~--N、NH_4~+-N的富集降低了土壤pH值.小叶锦鸡儿的栽植对沙土改良具有重要意义.     

成都平原菌渣还田下稻田田面水氮磷动态变化特征

为合理利用菌渣,以化肥施氮量为基准,设置1,1.5,2,2.5倍氮量的菌渣还田处理,采用田间定位监测并结合室内分析实验,以期通过研究稻田田面水中氮素和磷素的动态变化探明菌渣还田下面源污染风险。结果表明:与化肥处理相比,菌渣还田处理显著降低田面水TN、DTN、DON、PN和NH4+-N含量,显著提高NO3--N/TN比例(P0.05);其田面水TN、DTN和NO3--N含量在施肥后均呈下降趋势,NH4+-N含量则表现为"先增后减",施肥后第5d达最大值,其中TN、DTN和NH4+-N含量变化均可用指数降低模型Y=C0×ekt(k0)拟合,NO3--N含量变化可用倒数模型Y=C0+k/x拟合;受田面水中氮含量等因素的影响,其TP、DTP和PP含量均显著降低(P0.05),TP和DTP含量表现为"先降后升再降"。总体来看,较化肥处理,菌渣还田不会延长田面水氮磷素流失风险期,同时显著降低田面水NH4+-N含量,缩短NH4+-N流失风险期,但等氮量还田会显著降低水稻产量及糙米氮含量(P0.05),超过2倍氮量还田会增加NO3--N流失风险。综合环境风险与粮食生产,应以1.5倍氮量还田为宜。     

脲酶/硝化抑制剂双控下红壤性水稻土氮素变化特征

以红壤性水稻土为对象,设置大田试验处理:不施肥(CK)、单施氮肥(U)、氮肥配施0. 5%脲酶抑制剂N-丁基硫代磷酰三胺(NBPT)与1%硝化抑制剂3,4-二甲基吡唑磷酸盐(DMPP)(U+N/D)、氮肥配施1%NBPT与2%DMPP [U+2 (N/D)],研究4种施肥组合下双季稻土壤脲酶、土壤NH+4-N、田面水NH+4-N和NO-3-N的变化特征。结果表明,与CK和U处理相比,各施肥处理在施肥后第1～15 d,土壤脲酶活性、土壤NH+4-N、田面水NH+4-N含量增加,田面水NO-3-N含量无显著变化。与U+2 (N/D)处理相比,早稻中U+N/D处理的脲酶活性显著增加了0. 03～0. 70 mg·g-1,土壤NH+4-N含量显著增加了19. 11～61. 44 mg·kg-1,田面水NH+4-N含量显著增加了34. 48～40. 70 mg·L-1。相关分析表明,土壤NH+4-N与土壤脲酶、田面水NH+4-N均呈显著负相关,田面水NH+4-N与土壤脲酶、田面水NO-3-N均呈显著正相关(P 0. 05)。综上,与其他处理相比,U+N/D处理是在短期内有效提高土壤脲酶活性、土壤NH+4-N和田面水NH+4-N含量的最优处理,合理配施尿素及0. 5%脲酶抑制剂NBPT和1%硝化抑制剂DMPP能够显著提高NH+4-N供水稻吸收,减少氮素损失。     

江汉平原稻田田面水氮磷变化特征研究

在江汉平原地区,因水肥管理粗放,特别是人为排放刚施肥泡田水,水稻种植引发的氮磷面源污染问题比较严重,迫切需要掌握稻田氮、磷动态特征,并据此进行科学的肥水管理。采用大田试验的方法,设置不同氮磷梯度,研究了江汉平原稻田田面水氮磷形态与浓度动态变化特征及施肥的影响。结果表明:施尿素后,田面水可溶性总氮(DTN)、可溶性有机氮(DON)和铵态氮(NH_4~+-N)占总氮(TN)的比例分别在88.0%、44.7%和31.6%以上,且随施氮量增加而增大;施磷肥后,田面水中颗粒态磷(PP)占总磷(TP)的比例为76%～93%,且随施磷量的增加而降低。田面水中氮素浓度与施氮量之间呈分段线性相关关系,当施氮量分别超过287.8、289.9、231.5和336.7kg·hm-2后,TN、DTN、NH_4~+-N和DON的浓度会跃增;田面水中各形态磷素浓度均随施磷量的增加而线性增加。施氮肥后,田面水中TN和DTN浓度均在施肥后1 d达到峰值,在基肥和分蘖肥后5 d、穗肥后2 d降低至与不施氮肥基本接近;NH_4~+-N浓度在基肥和分蘖肥后2d、穗肥后1d达到峰值,基肥和分蘖肥后5 d、穗肥后2 d后降低至与不施氮肥趋同。施磷肥后TP、PP和可溶性总磷(DTP)的浓度均在施肥后1 d达到峰值,3 d后急剧降低,降幅均在79.0%以上。可见,在江汉平原地区,施尿素后田面水中氮素以DTN为主,尤其是DON和NH_4~+-N,施磷肥后以PP为主。减少氮、磷肥用量可降低稻田氮、磷损失,且氮肥施用量应尽可能控制在231.5 kg·hm-2以内。施基肥和分蘖肥后5 d内、施穗肥后2 d内是江汉平原稻田氮素损失的关键控制期,施磷肥后3 d内是磷素流失的关键控制期。     

太湖地区稻麦轮作农田氮素淋洗特点

通过排水采集器模拟试验研究了太湖地区不同施肥水平下农田N素淋洗特点.结果表明,N的渗漏损失以硝态氮(NO-3-N)为主,并发生在麦季,铵态氮(NH+4-N)淋洗量则很少,NO-3-N的量占渗漏液总N量的43%～72%,浓度为20～110mg/kg;渗漏水中N的含量与土壤N的淋洗量随施肥量的增加而增加,麦季土壤中NO-3-N的总淋洗量为17.8～58.5kg/hm2,平均为39.2kg/hm2,净淋洗量为5.5～40.7kg/hm2,平均为21.4kg/hm2,占施肥量的3.7%～12.2%;与纯化肥处理比较,化肥+猪粪处理增加了农田N的淋失,化肥+秸秆处理减少了土壤中N的淋失.与麦田渗漏水相比较,稻田渗漏水除水稻生长早期的部分样品外,NO-3-N和NH+4-N含量均很低,分别在1mg/kg和0.5mg/kg以下.     

秸秆还田下氮肥用量对稻田养分淋洗的影响

通过田间试验,研究秸秆还田配施氮肥对稻田土壤养分淋洗的影响。结果表明,随氮肥用量增加,田间渗漏水中NH4+-N、NO3--N、全氮浓度随之增加;与秸秆未还田相比,秸秆还田降低了田面水与渗漏水中NH4+-N、NO3--N的浓度;秸秆还田下各处理30cm土层渗漏水中全氮和NO3--N浓度最高,其浓度范围分别为1.09~12.76mg·L-1和0.76~3.74mg·L-1;全磷浓度范围为0.02~0.79mg·L-1,田面水中全磷浓度随施氮量增加而增加,30cm渗漏水中全磷浓度大于60cm渗漏水。氮肥用量180kg·hm-2时,施肥后5~10d内30cm、60cm渗漏水中的养分以NH4+-N为主,其后均以NO3--N为主。氮肥与秸秆配合施用,可降低田面水和渗漏水中的氮磷浓度,改善肥料利用效率。     

有机无机配施体系中有机肥腐熟程度对化肥氮利用率的影响机制

为探究有机肥腐熟度对配施化肥氮利用率的作用机制,利用~(15)N标记技术进行意大利生菜盆栽试验,从堆肥过程中选取不同腐熟度的有机肥[按照种子发芽指数(GI值)为50%、80%和100%进行堆肥的腐熟度区分],研究施~(15)NPK化肥(对照, CK)、~(15)NPK+GI 50%有机肥(GI50)、~(15)NPK+GI 80%有机肥(GI80)、~(15)NPK+GI 100%有机肥(GI100) 4个处理对意大利生菜化肥氮的转化、吸收和利用的影响。结果表明,与CK处理相比,添加有机肥处理意大利生菜生物量、~(15)N吸收量与~(15)N利用率分别显著提高30.5%～56.1%、 40.0%～91.0%和15.5%～41.8%(P0.05), GI80处理较GI50处理生物量、~(15)N吸收量与利用率分别显著提高17.1%、31.8%和35.4%(P0.05), GI100处理较GI50处理生物量、~(15)N吸收量与利用率分别显著提高19.6%、15.8%和22.8%(P0.05)。试验期间,添加有机肥处理较CK处理土壤~(15)NH_4~+-N显著提高44.9%～74.2%(P0.05), ~(15)NO_3~--N显著降低8.4%～38.1%(P0.05),净硝化率显著降低10.8%～24.6%(P0.05);GI80处理较GI50处理土壤~(15)NH_4~+-N提高7.9%～11.5%, ~(15)NO_3~--N显著降低18.5%～50.4%(P0.05),净硝化率显著降低15.0%～28.2%(P0.05);GI100处理较GI50处理土壤~(15)NH_4~+-N显著提高11.5%～26.9%(P0.05), ~(15)NO_3~--N显著降低15.8%～22.7%(P0.05),净硝化率显著降低12.5%～23.9%(P0.05)。土壤微生物量氮(MB~(15)N)缓慢上升,添加有机肥处理较CK处理显著提高67.3%～94.1%(P0.05),GI80处理较GI50处理提高6.0%～23.8%,GI100处理较GI50处理显著提高6.9%～25.5%(P0.05)。各处理MB~(15)N占MBN的54.9%～71.6%(P0.05)。相关分析结果表明, MB~(15)N、~(15)NH_4~+-N与~(15)N吸收量、~(15)N利用率呈现极显著正相关关系,且RDA分析结果说明MB~(15)N是影响化肥~(15)N吸收利用的关键驱动因子。因此,有机无机配施体系中适当增加有机肥的腐熟度(GI≥80%)能够明显增强土壤微生物的固氮能力,提高土壤氮素水平,减缓土壤铵态氮向硝态氮的转化速度,降低土壤净硝化速率,从而提高化肥氮的利用效率。     

祁连山哈溪林区移植前后土壤氮对比研究

研究不同海拔梯度森林土壤氮的分布特征,对于合理利用森林资源、改善森林的生态功能都有重要意义。采用封顶埋管法,对祁连山东段哈溪林区不同海拔梯度和不同植被类型的土壤氮进行了研究。结果表明:(1)海拔2 650m青海云杉林土壤的初始TN,NH_4~+-N和NO_3~--N含量均最低,海拔2 950 m青海云杉林土壤的初始TN,NH_4~+-N和NO_3~--N含量均最高;各海拔梯度青海云杉林土壤经培养后,其TN,NH_4~+-N和NO_3~--N含量均减小。(2)就不同植被类型而言,青海云杉林土壤TN,NH_4~+-N和NO_3~--N含量均最高,草地和灌丛土壤TN,NH_4~+-N和NO_3~--N含量较低,且二者差异不大。草地和灌丛土壤培养后TN和NH_4~+-N含量显著升高,NO_3~--N含量变化不大。(3)某一海拔青海云杉林土壤移植到其他海拔青海云杉林培养后,土壤TN,NH_4~+-N和NO_3~--N含量变化不大;不同植被类型之间土壤相互移植培养后,土壤TN,NH_4~+-N和NO_3~--N含量变化明显,不同植被类型对土壤氮的含量差异显著。     

两种典型温度下农村化粪池出水氮素在原地土壤中的迁移转化过程

为探究典型温度下(25℃和5℃)农村化粪池出水氮素在排污口原地土壤中的迁移转化过程,采集原地表层土壤及化粪池出水,构建室内模拟系统,分析化粪池出水经土壤渗滤前后氮素组成。结果表明,农村化粪池出水氮素以可溶性无机氮(DIN)为主,其中NH_4~+-N占70%以上;两种温度条件下化粪池出水DIN差异不显著(P0.05,n=12),NH_4~+-N、NO_2~--N、NO_3~--N浓度均具有极显著性差异(P0.01,n=12),25℃时硝化作用明显,导致出水NH_4~+-N低于5℃,NO_2~--N、NO_3~--N高于5℃;两种温度条件下原地土壤对化粪池出水DIN均有削减作用,其中NH_4~+-N削减量均占DIN削减量60%以上;25℃和5℃条件下,NH_4~+-N削减率分别为23.11%～47.37%和25.37%～43.47%;25℃时NH_4~+-N削减主要通过氨挥发、反硝化、厌氧氨氧化等作用完成,而5℃时NH_4~+-N削减主要通过土壤NH_4~+-N吸附作用完成;25℃时土壤对NO_3~--N还存在蓄积作用。研究表明,两种温度下化粪池出水NO-_2~--N和NO_3~--N在原地土壤中可发生反硝化或异化还原作用进而得到削减。     

太湖地区稻麦轮作农田氮素淋洗特点

通过排水采集器模拟试验研究了太湖地区不同施肥水平下农田N素淋洗特点。结果表明,N的渗漏损失以硝态氮（NO3^--N）为主,并发生在麦季,铵态氮（NH4^ -N)淋洗量则很少,NO3^--N的量占渗漏液总N量的43%-72%,浓度为20-110mg/kg;渗漏水中N的含量与土壤N的淋洗量随施肥量的增加而增加,麦季土壤中NO3^--N肥量的3.7%-12.2%;与纯化肥处理比较,化肥 猪粪处理增加了农田N的淋失,化肥 秸秆处理减少了土壤中N的淋失,与麦田渗漏水相比较,稻田渗漏水除水稻生长早期的部分样品外,NO3^--N和NH4^ -N含量均很低,分别在1mg/kg和0.5mg/kg以下。     

粪肥对不同磷水平土壤磷流失潜力的影响

田间试验结果表明,因施肥方式不同,粪肥施用对不同磷水平土壤磷流失潜力的影响也不相同。在施用的粪肥与表土混合的情况下,粪肥对土壤磷流失的增加量随土壤磷水平的提高而升高。但当粪肥表施不与土壤混合时,情况有所不同。在粪肥表施初期,无论是高磷土壤还是低磷土壤,地表径流中磷浓度都达到较高水平,施肥引起的土壤磷流失的增加量以低磷土壤更为明显。但粪肥表施较长时间后,粪肥对土壤磷流失的增加量也随土壤磷水平的提高而升高。总的来说,控制地表径流磷流失的效果是粪肥与土混施优于表施,流域内粪肥处置应优先施于土壤磷水平较低的土壤中。     

长期定位施肥对棕壤有机碳的影响

通过对棕壤有机肥和化肥长期定位施肥的研究表明,长期施肥对耕层土壤有机碳含量和有机碳储量有显著性影响(P<0.05)。与试验前土壤相比,施用有机肥能显著增加土壤有机碳含量和储量;当有机肥和无机肥配合施用时,其促进作用明显大于单施化肥。单施化肥能够提高土壤有机碳含量和储量,但增加幅度不大。经过26年施肥,不同层次土壤有机碳含量有一定程度的升高,随着土层的加深,有机碳含量迅速下降,各处理之间无明显差异。     

有机无机肥配施对酸性菜地土壤硝化作用的影响

通过室内培养和田间试验, 研究了有机无机肥配施对酸性菜地土硝化作用的影响。培养试验条件为60%土壤最大持水量和25 ℃。 结果表明,土壤硝化作用模式为指数方程,延滞期10天。与纯化肥处理（NPK）相比,鲜猪粪配施无机肥（FPM+NPK）和猪粪堆肥配施无机肥（CPM+NPK）均能降低土壤硝化势和氨氧化潜势,猪粪堆肥配施无机肥还能增加土壤微生物量碳、 氮。鲜猪粪配施无机肥和猪粪堆肥配施无机肥处理在硝化培养和田间试验期间N2O释放量均没有差异,但硝化培养期间鲜猪粪配施无机肥的N2O释放量显著低于纯化肥处理,田间试验期间猪粪堆肥配施无机肥的N2O释放量显著低于纯化肥处理。培养试验结束后的土壤pH值与土壤硝化势间,以及硝化培养期间N2O累积释放量与土壤硝化势间均存在显著正相关关系。本研究表明, 有机无机肥配施显著影响土壤硝化作用以及硝化培养期间和田间N2O释放。     

Movement of Faecal Bacteria through the Vadose Zone

The impact of biosolid and soil type on the movement of faecal coliforms through the vadose zone was investigated following the application of animal manure to soil. Two types of biosolid, solid and liquid manure, were applied to two soil types at a wide range of initial water contents. Bacteria present in the soil solution were collected using calibrated ceramic-porous-cup samplers. Estimated bacterial migration velocities in the soil profile were consistent with the hypothesis that bacteria move mostly through soil macropores, as the rate of transport was faster than the average pore-water velocity. Macropore transport was more likely to occur in wet soils, but it was not necessarily restricted to soils with high initial soil water content. A larger soil clay content, lower total soil porosity, and lower saturated hydraulic conductivity resulted in a greater likelihood that suspended bacteria would be funnelled through pores of larger diameter and faster pore water velocity, increasing the potential vertical transport length of bacteria through the vadose zone. Total porosity was not a significant factor in enhancing deep transport of faecal bacteria. The potential of faecal bacteria to be transported to depth in soil was correlated with the water content of the manure. We conclude that application of animal manure to soil can readily lead to groundwater contamination with faecal bacteria especially under moist soil conditions, and that macropores are important in the transport.     

The Effects of Long‐term Fertiliser Applications on Soil Organic Carbon and Hydraulic Properties of a Loess Soil in China

Based on a 28‐year in situ experiment, this paper investigated the impacts of organic and inorganic fertiliser applications on soil organic carbon (SOC) content and soil hydraulic properties of the silt loam (Eumorthic Anthrosols) soils derived from loess soil in the Guanzhong Plain of China. There were two crop (winter wheat and summer maize) rotations with conventional tillage. The treatments included control without fertiliser application, organic manure application (M), chemical fertiliser application (NP), and the application of organic manure with chemical fertiliser (MNP). The results showed that the 28‐year organic manure applications (M and MNP) significantly (p < 0·05) increased SOC content at surface layer (0–10 cm), but the effect of chemical fertilisers alone on SOC was not significant. Organic manure treatments (M and MNP) apparently improved soil hydraulic properties. Compared with control, field capacity and total porosity significantly (p < 0·05) increased while soil bulk density significantly (p < 0·05) decreased for organic manure applications. The M and MNP treatments increased soil water retentions by 3·2–10·8%, which was dependent of suction tensions. However, the NP treatment had no significantly impact on soil water retention compared with control. Neither organic nor inorganic fertiliser applications significantly changed saturated hydraulic conductivity. However, a clear difference was observed for unsaturated hydraulic conductivity between the M and the control at 0–5 cm. Overall, long‐term applications of organic manuring increased SOC content and amended soil hydraulic properties. However, the effects of chemical fertilisers on these soil properties were limited. Copyright © 2015 John Wiley & Sons, Ltd.     

Cattle manure effects on structural stability and water retention capacity of a granitic sandy soil in Zimbabwe

The evaluation of soil aggregate stability and water retention is important in the assessment of soil management options. A 3-year study was conducted in 1999 to determine the effects of two cattle manure application methods on soil aggregate stability and water retention capacity of a sandy soil (Haplic Lixisol). Manure application increased soil organic C by 10–38% in the 0–10 cm layer. Compared with the control, manure management treatments increased the aggregate stability of soil as measured by the mean weight diameter (MWD) and aggregates between 2 and 10 mm (AGG2) indices from 0.243 to 0.733–0.926 mm, and from 27.3 to 128.3–148.3 g kg⁻¹, respectively. The readily available water (RAW) capacity of the soil was significantly increased by manure addition, whereas the increase in AWC was not significant. The increase in water retention capacity in the soil was more affected at low suctions and this was related to the effects of manure on macroporosity. It was concluded that cattle manure was beneficial to the structural stability and water retention of this soil.     

有机肥长期施用对设施土壤全镉和有效态镉含量的影响

应用长期田间定位试验方法,比较研究了长期有机肥不同施肥方式（不施肥、有机肥常量、有机肥减量及有机肥减量配施化肥）对设施土壤镉（Cd）全量及有效态含量的影响,同时考察了其对土壤特性的影响及二者的相关性。结果表明：与不施肥的设施土壤（对照）相比,长期定量施用有机肥土壤表层（0～20 cm）Cd全量显著降低,且随着施用量下降,这种效果更显著,但对亚表层（20～40 cm）Cd全量无显著影响。长期施用有机肥会提高设施土壤表层Cd有效态含量,特别是0～10 cm土壤有效态Cd含量显著高于对照,但与有机肥常量处理相比,有机肥减量和有机肥减量配施化肥处理土壤有效态Cd含量分别显著降低了17.56%和14.04%;同时,有机肥减量配施化肥对设施土壤有机质、全氮、表层有效磷均有大幅提升,且pH偏高于有机肥常量。相关分析表明,设施土壤有机质、有效磷含量均与土壤Cd全量和有效态含量之间呈显著或极显著正相关,土壤全氮含量与Cd有效态含量呈显著正相关,pH与有效态含量之间呈极显著负相关。上述结果表明有机肥适当减施,同时辅以适量化肥,可进一步改善设施土壤特性,进而控制设施土壤表层Cd累积。     

连续施用酸化粪水对土壤养分淋溶及重金属累积的影响

为探索连续施用酸化粪水对土壤养分淋溶及重金属累积情况的影响,采用新鲜粪水和酸化粪水,开展土柱淋溶试验。试验分别设置1个对照组、新鲜粪水和3个不同pH值（6.5、6.0和5.5）的酸化粪水,每个处理分别设置6次粪水淋溶。结果表明：施用新鲜粪水和酸化粪水均能增加土壤养分,施用新鲜粪水、pH值6.5、pH值6.0和pH值5.5的粪水后土壤总养分（N、P、K）的增长幅度分别为1%～40%、15%～66%和5%～21%,重金属Cu和Zn的增长幅度为4%～48%和4%～11%,重金属Cd和Pb的增长幅度为2%～14%和1%～18%;连续施用酸化粪水会使土壤pH降低、土壤电导率值升高以及土壤重金属不断累积,这也是导致土壤环境遭到破坏的风险因素,实际应用过程中应特别注意;建议每两季作物施用一次pH值为6.5的粪水;每三季作物施用一次pH值为6.0的粪水;每四季作物施用一次pH值为5.5的粪水。该研究通过对比分析连续施用新鲜粪水和不同pH值的酸化粪水后土壤养分和重金属浓度的变化,探讨了酸化粪水的还田效果,为连续施用酸化粪水的研究提供技术支撑。     

化肥有机肥配合施用下双季稻田氮素形态变化

为揭示有机无机肥配合施用下稻田氮素的动态及迁移特征,在湘南双季水稻农作区第四纪红土发育的红黄泥稻田上进行了连续6年田间试验。通过比较不施氮肥（PK）、施用有机肥猪粪（M）、化肥（NPK）及有机肥化肥配合（NPKM）,研究稻田表层全氮、无机氮动态变化,不同层次（25—30、55—60、85—90 cm）土壤溶液无机氮动态,耕层土壤无机氮动态等。结果表明,NH4+-N是红壤双季稻田无机氮素存在的主要形态,施用化学肥料处理（NPK）施肥后1～3 d表面水NH4+-N浓度占全氮比例可达0.5～0.9,有机肥处理（M）为0.3左右。不同层次土壤溶液及其土壤氮素浓度呈现一致的特征,即施肥后短期内出现浓度峰值随后迅速下降,且随着往下推移,氮素峰值出现时间延长,表层水全氮及无机氮在施肥后1～2 d出现浓度高峰,耕层土壤及25—30 cm土壤溶液无机氮浓度高峰约在施肥后3～5 d。化肥有机肥配施有利于水稻稳产高产,年产量达12.2 t/hm2,比不施氮肥的对照产量（7.3 t/hm2）增加68%;土壤有机质6年提升18.5%,显著高于化肥。施用有机肥（M）及有机无机肥配合（NPKM）显著降低了稻田表层水全氮及不同层次土壤溶液和耕层土壤NH4+-N峰值浓度,提高水稻产量和培肥土壤,有利于减少当前氮肥过量施用带来的环境负荷。     

Precision Manure Management on Site-Specific Management Zones: Topsoil Quality and Environmental Impact

Maintenance and improvement of soil quality across spatially variable soils in continuous cropping systems are critical to sustaining agricultural productivity and environmental quality. The objectives of this project were (i) to study the effects of variable-rate application of animal manure on selected topsoil quality parameters across site-specific management zones (MZs) and (ii) to evaluate the variable-rate applications of manure using risk-assessment tools of nitrogen (N) leaching and phosphorus (P) runoff indices to understand its impact on environmental quality. This study was conducted in northeastern Colorado on continuous and furrow-irrigated maize fields. Experimental strips, 4.5 m wide and 540 m long, spanned across all MZs with treatments nested within MZs in the field. Variable rates of dairy and beef feedlot manure applied on irrigated and dryland fields respectively ranged from 0 to 67 Mg ha^?1. Surface soil quality parameters evaluated before and after this study included bulk density, organic matter, water-holding capacity, electrical conductivity, and particle-size analysis. Results indicate that animal manure applications of 44 and 67 Mg ha^?1 significantly (P ≤ 0.05) increased soil organic matter and decreased bulk density of low- and medium-productivity-level MZs and had no significant impact on surface soil organic matter and bulk density of the high-productivity-level MZs. Animal manure significantly (P ≤ 0.05) increased surface soil water-holding capacity and soil electrical conductivity across zones; however, the maximum manure-induced soil EC was 1.0 dS m^?1, which was below levels regarded as potentially harmful for maize production. Soil texture was not affected by animal manure applications. Colorado N leaching and P index indicated no environmental hazard associated with variable rate application of animal manure across MZs. This study indicates that variable-rate application of animal manure across MZs has potential to improve or maintain soil quality parameters over time without impairing the environment.