J. Keith Syers

Contribution of livestock excreta to nutrient balances

J. Lingard, W. Sheldrick, John Lingard, 2003, Nutrient Cycling in Agroecosystems.

Impacts of fertilizer practices on environmental risk of nitrate in semiarid farmlands in the Loess Plateau of China

Wenzhao Liu, Yong Li, Jinshui Wu, 2010, Plant and Soil.