GIS-based soil fertility assessment of a micro-watershed of semi-arid tropics in southern India

Abstract

Available macronutrient status in the soil of Chotanahalli micro-watershed (468 ha) in Kunigal Taluk, Tumkur district was studied with the aid of GIS. Forty three surface soil samples at 320 m grid were collected from Chotanahalli micro-watershed and assessed for the soil organic carbon, available nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. Results revealed that the ranges of SOC, available N, P and K were 2.1 to 7.5 g kg-1, 282.2 to 526.8 kg N ha-1, 8.0 to 67.6 kg P2O5 ha-1 and 124.3 to 338.5 kg K2O ha-1, respectively. Spatial interpolation revealed that majority (321 ha) of the watershed was low in SOC, whereas the whole watershed was medium in available N, P and K. In case of secondary nutrients, available S was found to be medium in majority (423.4 ha) of the area, whereas, exchangeable Ca and Mg were found sufficient in the whole watershed. The Nutrient Index values indicated that the micro-watershed was under “medium” category for available nitrogen, phosphorus, potassium and sulphur, whereas, it fell under “low” category with respect to organic carbon. Measures to improve the status of SOC should be taken up in the study area for sustainable production of crop.

Physico-chemical properties, available nutrient content and their inter-relationship in soils under rain fed maize-wheat cropping system, district Reasi (J&K)

“…The role played by organic matter in maintenance of soil fertility in more than one ways is well established (Johnston, 1986) which is also evident from highly significant positive correlation (r=0.99 ** ) between the two as found in the present studies (Table 4). These results are comparable with the findings of Kumar et al (2022) and Singh and Singh (2022) where available N in soils had significant positive correlations with soil OC. High levels of OM not only provide part of the N requirement of crop plants but also enhance nutrients and water retention capacity of soils and creates favourable physical, chemical and biological environment.…”