ASSESSMENT OF SOIL NUTRIENT DEPLETION UNDER INTENSIVE FARMING SYSTEMS

Abstract

The intensive agricultural systems are increasingly becoming geared towards the high-input approaches in order to meet food needs of the world yet this extractive process is in most cases leading to severe depletion of the essential soil nutrients, particularly nitrogen, phosphorous and potassium, made worse by the shallow monitoring applications that do not take into account the dynamics of the subsoil. This experiment investigated depth based nutrient interactions, microbial interactions and deep placement performance and combined nutrient regulation in 3 agroecological sites with a long period of continuous agricultural practices. The four stratification (060 cm) cropping cycle with mass balance of the soil in terms of vertical diffusion (kdiff = 0.04-0.89 cm 2 day -1 ) and root uptake efficiency (eta = 0.06-0.52) were performed. The results indicated that the traditional surface broadcast fertilization (T1) produced a high level of vertical stratification and therefore the nitrogen 12 kg ha -1 and -1 loss was at the surface and depth respectively. Deep placement of deep banded phosphorus (10 -15 cm (T2)) and potassium (10 -15 cm (T2)) showed 10 -15 percent higher nutrient recovery rates (nitrogen: 58.9, phosphorus: 44.2, potassium: 67.8) than integrated nutrient management which included deep placement of compost The implications of these results are that the substitution of surface dominated and mineral dominated fertilization with depth targeted and integrated nutrient management, reestablishes vertical nutrient continuity, enhances biological cycling and reduces environmental losses, therefore, provides a mechanistic policy relevant solution to resilient soil management.