Drury C F, Tan C S, Welacky T W, Reynolds W D, Zhang T Q, Oloya T O, McLaughlin N B, Gaynor J D
J Environ Qual. 2014 Mar;43(2):587-98. doi: 10.2134/jeq2012.0495.
Nitrate lost from agricultural soils is an economic cost to producers, an environmental concern when it enters rivers and lakes, and a health risk when it enters wells and aquifers used for drinking water. Planting a winter wheat cover crop (CC) and/or use of controlled tile drainage-subirrigation (CDS) may reduce losses of nitrate (NO) relative to no cover crop (NCC) and/or traditional unrestricted tile drainage (UTD). A 6-yr (1999-2005) corn-soybean study was conducted to determine the effectiveness of CC+CDS, CC+UTD, NCC+CDS, and NCC+UTD treatments for reducing NO loss. Flow volume and NO concentration in surface runoff and tile drainage were measured continuously, and CC reduced the 5-yr flow-weighted mean (FWM) NO concentration in tile drainage water by 21 to 38% and cumulative NO loss by 14 to 16% relative to NCC. Controlled tile drainage-subirrigation reduced FWM NO concentration by 15 to 33% and cumulative NO loss by 38 to 39% relative to UTD. When CC and CDS were combined, 5-yr cumulative FWM NO concentrations and loss in tile drainage were decreased by 47% (from 9.45 to 4.99 mg N L and from 102 to 53.6 kg N ha) relative to NCC+UTD. The reductions in runoff and concomitant increases in tile drainage under CC occurred primarily because of increases in near-surface soil hydraulic conductivity. Cover crops increased corn grain yields by 4 to 7% in 2004 increased 3-yr average soybean yields by 8 to 15%, whereas CDS did not affect corn or soybean yields over the 6 yr. The combined use of a cover crop and water-table management system was highly effective for reducing NO loss from cool, humid agricultural soils.
农业土壤中流失的硝酸盐对生产者来说是一种经济成本,当其进入河流和湖泊时会引发环境问题,而当其进入用于饮用水的水井和含水层时则会带来健康风险。与不种植覆盖作物(NCC)和/或传统的无限制瓦管排水(UTD)相比,种植冬小麦覆盖作物(CC)和/或采用可控瓦管排水-次灌溉(CDS)可能会减少硝酸盐(NO)的流失。开展了一项为期6年(1999 - 2005年)的玉米-大豆研究,以确定CC + CDS、CC + UTD、NCC + CDS和NCC + UTD处理在减少NO流失方面的有效性。连续测量了地表径流和瓦管排水中的流量和NO浓度,与NCC相比,CC使瓦管排水水中5年流量加权平均(FWM)NO浓度降低了21%至38%,累积NO流失减少了14%至16%。与UTD相比,可控瓦管排水-次灌溉使FWM NO浓度降低了15%至33%,累积NO流失减少了38%至39%。当CC和CDS结合使用时,与NCC + UTD相比,5年累积FWM NO浓度和瓦管排水中的流失量分别降低了47%(从9.45降至4.99毫克氮/升,从102降至53.6千克氮/公顷)。CC条件下径流减少以及瓦管排水相应增加,主要是由于近地表土壤水力传导率增加所致。覆盖作物使2004年玉米籽粒产量提高了4%至7%,使3年平均大豆产量提高了8%至15%,而CDS在6年期间未对玉米或大豆产量产生影响。覆盖作物和地下水位管理系统的联合使用对于减少凉爽湿润农业土壤中的NO流失非常有效。