@article {Wang58, author = {Q. Wang and Y. Li and W. Klassen}, title = {Influence of summer cover crops on conservation of soil water and nutrients in a subtropical area}, volume = {60}, number = {1}, pages = {58--63}, year = {2005}, publisher = {Soil and Water Conservation Society}, abstract = {To elucidate the effects of summer cover crops on vegetable production, on soil water conservation and on reducing nutrient leaching from the soil, a pot experiment was conducted on Krome soil with legume and non-legume cover crops. Natural weedy fallow served as the control. The cover crops were sunn hemp (Crotalaria juncea L.), cowpea (Vigna unguiculata (L. Walp)), velvetbean (Mucuna deeringiana (Bort.) Merr.), and sorghum sudangrass (Sorghum bicolor x S. bicolor var. sudanense (Piper) Stapf). The leachate from under each pot was collected weekly, measured, and analyzed for concentrations of nitrate (NO3-N), ammonium (NH4-N) and inorganic phosphorus (P). The results showed that compared to the control, legume cover crops, especially sunn hemp, significantly improved tomato yields, and all the cover crops significantly reduced water and nutrient leaching. The amounts of NO3-N in the leachates collected during six-week period from pots with cover crops was equivalent to 0.9 to 2.2 kg ha-1(0.8 to 2.0 lb ac-1), which was significantly less than 16.1 kg ha-1 (14.4 lb ac-1) from the weedy fallow (control). In the fallow treatment, 21.3 percent of fertilizer nitrogen (N) was lost through leaching, but only 1.3 to 3.2 percent was lost with cover crops. Taking account of plant uptake and leaching, total amounts of 26.9 and 40.6 kg N ha-1 (24.0 and 36.3 lb ac-1) were lost from the soil pool for the treatments in fallow and sorghum sudangrass but 28 to 252.7 kg N ha-1 (25.0 to 225.7 lb ac-1) were obtained mostly by N fixation via rhizobia and accumulated in leguminous cover crops. Although relative amounts of fertilizer P lost via leaching were meager for all treatments, at least twice as much was lost from fallow (0.4 percent) rather than from treatments with cover crops (0.1 to 0.2 percent). Compared to the control (fallow with weeds), velvetbean and sunn hemp reduced inorganic P losses by 70 percent and 66 percent, while cowpea and sorghum sudangrass reduced losses by only 19 percent and 13 percent. Leguminous cover crops reduced leachate volume by 55 percent to 91 percent, sorghum sudangrass reduced leachate by 61 percent, while fallow soil with natural weeds only reduced leachate by 48 percent of applied water. The results suggest that summer leguminous cover crops can not only prevent the loss through leaching of 88 to 94 percent of soil N and of 50-83 percent of inorganic P but also accumulated 2.0 to 8.7 fold more N in the plants, which contribute to improving the subsequent vegetable yield after returned to the soil.}, issn = {0022-4561}, URL = {https://www.jswconline.org/content/60/1/58}, eprint = {https://www.jswconline.org/content/60/1/58.full.pdf}, journal = {Journal of Soil and Water Conservation} }