Daverede I C, Kravchenko A N, Hoeft R G, Nafziger E D, Bullock D G, Warren J J, Gonzini L C
Dep. of Crop Sciences, 1102 S. Goodwin Ave., Univ. of Illinois, Urbana, IL 61801, USA.
J Environ Qual. 2003 Jul-Aug;32(4):1436-44. doi: 10.2134/jeq2003.1436.
Continued inputs of fertilizer and manure in excess of crop requirements have led to a build-up of soil phosphorus (P) levels and increased P runoff from agricultural soils. The objectives of this study were to determine the effects of two tillage practices (no-till and chisel plow) and a range of soil P levels on the concentration and loads of dissolved reactive phosphorus (DRP), algal-available phosphorus (AAP), and total phosphorus (TP) losses in runoff, and to evaluate the P loss immediately following tillage in the fall, and after six months, in the spring. Rain simulations were conducted on a Typic Argiudoll under a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. Elapsed time after tillage (fall vs. spring) was not related to any form of P in runoff. No-till runoff averaged 0.40 mg L(-1) and 0.05 kg ha(-1) DRP and chisel-plow plots averaged 0.24 mg L(-1) and 0.02 kg ha(-1) DRP concentration and loads, respectively. The relationship between DRP and Bray P1 extraction values was approximated by a logistic function (S-shaped curve) for no-till plots and by a linear function for tilled plots. No significant differences were observed between tillage systems for TP and AAP in runoff. Bray P1 soil extraction values and sediment concentration in runoff were significantly related to the concentrations and amounts of AAP and TP in runoff. These results suggest that soil Bray P1 extraction values and runoff sediment concentration are two easily measured variables for adequate prediction of P runoff from agricultural fields.
肥料和粪肥的投入持续超过作物需求，导致土壤磷（P）含量增加，农业土壤的磷径流也随之增多。本研究的目的是确定两种耕作方式（免耕和凿式犁耕）以及一系列土壤磷水平对径流中溶解态活性磷（DRP）、藻类可利用磷（AAP）和总磷（TP）浓度及负荷的影响，并评估秋季耕作后和春季六个月后磷的流失情况。在一种典型的暗沃土上，以玉米（Zea mays L.）-大豆[Glycine max (L.) Merr.]轮作模式进行了降雨模拟。耕作后的时间（秋季与春季）与径流中任何形式的磷均无关联。免耕径流中DRP平均浓度为0.40 mg L(-1)，负荷为0.05 kg ha(-1)；凿式犁耕小区的DRP浓度和负荷分别平均为0.24 mg L(-1)和0.02 kg ha(-1)。免耕小区的DRP与Bray P1提取值之间的关系可用逻辑函数（S形曲线）近似表示，而翻耕小区则可用线性函数近似表示。两种耕作系统的径流中TP和AAP未观察到显著差异。Bray P1土壤提取值和径流中的沉积物浓度与径流中AAP和TP的浓度及含量显著相关。这些结果表明，土壤Bray P1提取值和径流沉积物浓度是用于充分预测农田磷径流的两个易于测量的变量。
