Trend setting impacts of organic matter on soil physico-chemical properties in traditional vis -a- vis chemical-based amendment practices

Abstract

Amongst the soil qualities that are taken into consideration while quantifying the fertility status of soil for agri-production, the properties of water holding capacity, bulk density, electrical conductivity and soil pH play crucially important roles, directly as well as indirectly. The role of organic matter content of soil in altering the aforesaid properties occurs through various complex interactions. In our study we attempted to understand the impact of amendments in traditional ecological knowledge (TEK)-based organic input agri-management systems (A1), versus conventional chemical-intensive agri-systems (A2) in altering/modifying the few important properties viz soil organic matter (SOM), pH, electrical conductivity (EC), bulk density, and water holding capacity of the soil in the three different crop phases viz. pre, mid and the post-harvest, spread over six cropping seasons in four years. The study area was a geo-ecologically unique terrain of Kachchh, Western India. Natural stressors as erratic rainfall, drought and salinity are a typical feature of this zone. Physico-chemical soil attributes have shown significant differences in the amendment systems. The application of organic manures and concoctions likeJivamritfrom indigenous knowledge base of local farming community, certainly rendered better organic matter content that affect soil structure and stability, which in turn affected the maximum water holding capacity (MWHC), which was significantly higher in A1 (47.53%; (Standard Error [SE] = ±0.92%) across phases and seasons than A2 (37.99%; SE = ±0.74%). Probably, for the same reason, amendments with organic inputs had a lower bulk density (1.04 g/cm3; SE = ±0.02 g/cm3) as compared to amendments with no or very few organic inputs (1.31 g/cm3; SE = ± 0.03 g/cm3).The reduction in pH and electrical conductivity in A1 may be ascribed to increased amounts of SOM as a result of addition of green manures and organic concoctions. Even during the stressed period of drought in cropping seasons of season 2 (Kharif2012) and season 3 (Rabi 2012–2013) this trend was followed. This clearly shows that salinity endurance and drought resistance are remarkable features of organically amended soils and this resilience to drought is achieved over continual usage of organic manures. The arid and semi-arid tropics are highly prone to stressors like drought, highly erratic rainfall patterns, and salinity, and the present study advocates the supremacy of TEK-based agri-management systems in soil sustainability for maintaining the soil fertility in the long run.