Spatial Variability of Soil Properties under Different Land Use Systems in Wokha District of Nagaland, India

The shifting cultivation practice is the predominant land use system of Nagaland, India, and Wokha district in particular. In general, there are four different forms of land use: forest, shifting cultivation, cultivated fallow, and wet terrace rice cultivation. In the Wokha district, a study was conducted in the year 2015 to evaluate the variability in soil characteristics among four different land use systems and to map their spatial distribution. A total of 381 soil samples were collected and tested for six soil fertility parameters; clay, pH, soil organic carbon, available nitrogen (N), phosphorus (P) and potassium (K). The results showed that all of the soils were very acidic in nature; however the mean value of soil pH was substantially higher in the shifting cultivation system. Soil organic carbon concentrations ranged from high to very high across all land use systems. Average soil organic carbon content was highest in the forest, followed by cultivated fallow, shifting, and wet terrace rice cultivation (WTRC) systems, whereas available N content was very low to low. The P concentration of the soil was very low in the WTRC system and low in the other systems. Soil K concentration was high in shifting (361.95 kg/ha), cultivated fallow (312.4 kg/ha), forest (309.73 kg/ha), and low in WTRC (166.975 kg/ha) land use systems. Available N, P and K deficiency was found in 93.8%, 72.2%, and 32.9% of soil samples, respectively. Soil organic carbon correlated positively with K and significantly positively with N. Soil pH correlated negatively with clay content and positively but non-significantly with P. The generated maps might be used to assist farmers in identifying the expected nutrient levels in their areas and encourage them to change their crop management practices to improve crop yield and profitability. Due to soil acidity, higher SOC, lower N and P, and higher potassium content, suitable acid loving crops, higher N and phosphorus fertilization, and some commercially advantageous potassium responsive crops may be encouraged in farming practices.