An integrated approach towards sustainable soil and water quality management

Abstract

Understanding the influence of legumes, used as winter cover crops or under-seeded in row-crops, on soil N dynamics is critical in developing sustainable soil and water quality management strategies. An incubation experiment was carried out to determine the influence of intrinsic soil properties and bulk density on N-mineralization subsequent to red clover incorporation and to develop equations to predict N-mineralization as a function of intrinsic soil properties. The soils used in this study had different intrinsic properties. Air-dried and ground red clover shoot material was mixed with soil,< 4 mm, to provide 140 kg N ha-1 (75 mg legume-N kg-1) and incubated for 72 d. The size of the potentially mineralizable resistant N-pool, N,, in the red clover added treatment ranged from 28.2 to 68.1 mg kg-1 and that of the labile pool, Nl, from 10.3 to 27.1 mg kg-1. The corresponding range in rate constant, kr, of the resistant pool was from 0.0038 to 0.0065 d-1 and that of the labile pool, kl, ranged from 0.0081 0.060 d-1. The pedotransfer function, PTF, analysis indicated that Nl, kl, N, and kr are functions of soil properties; clay, silt, CEC, organic matter, CaC03, total N, C:N ratio, and bulk density. The PTF's approach eliminated the need for labour intensive, laborious, and time consuming incubation experiments to predict legume N-mineralization, thereby enabling the development of best N-management practices and reduce N leaching.