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Assessing soil fertility is crucial for developing effective soil management strategies that can enhance soil health, increase crop productivity, and promote sustainable agricultural practices. The current study was conducted to assess the soil fertility index and, to prepare a soil fertility zonation map using combine fuzzy and analytical hierarchy process (AHP) approaches in Udham Singh Nagar of Uttarakhand. Sixty GPSbased surface soil samples were collected (0-30 cm depth) from different locations, and analyzed chemical properties using a stratified multistage random sampling method and maps were prepared to identify their spatial distribution. The results show that the values of soil fertility index on the fuzzy scale (0-1) was varied from 0.04-0.62 and, therefore, the study area was classified as very low, low, and moderate soil fertility classes comprising 55.61%, 44.24% and 0.14%, respectively. AHP analysis revealed that the most important limiting factor for wheat production was available nitrogen, followed by phosphorous, potassium, organic carbon, pH and electrical conductivity. A correlation coefficient between wheat yield and soil fertility index was found to be as high as 0.86, and its validating the zonation of soil fertility classes. This study infers that combined fuzzy-AHP techniques may be used to compute soil fertility index and limiting factors of wheat production.

During Rabi 2018-19, an Inceptisol field test was conducted at the Agriculture Research Farm at Banaras Hindu University, Varanasi, using STCR technique, from which fertiliser recommendation equations for oat (Avena sativa L.) may be developed. Soil test results, oat fresh forage yield and NPK uptake by oat crop were used to attain four essential basic parameters, i.e., nutrients required to produce one quintal of fresh forage (NR), fertilizer contribution of nutrients (% CF), soil nutrient contribution (% CS) and organic matter contribution from FYM (CFYM). A quintal of fresh forage required 0.26, 0.04, and 0.30 Kg of N, P2O5 and K2O, respectively. Soil Nutrient Contribution Proportions (CS%): 35.81, 48.44, and 64.87 N, P2O5, and K2O, respectively. N, P2O5, and K2O percent added through fertilizer alone (CF %) and FYM alone (CFYM) were 59.17, 47.38, and 115.25; 24.19, 5.82, and 2.33, respectively. The ready reckoner doses of fertilizer were emphasized on these specific criteria for various soil test values and required to make recommendations for fresh forage oat yields for NPK alone and NPK + FYM.

No other element can match the essentiality of nitrogen in soil for growth and development of plants and its transformations among various forms viz., nitrite, nitrate, ammonium are mostly mediated by microbes. As its transformation depends on major microbial activity and thus, there is a huge difference between the transformation of it in aerobic soil and anaerobic soil. This difference mainly arises due to presence and absence of oxygen. The absence of oxygen in soil creates anaerobic condition and thus promotes the growth of anaerobic microbes. In submerged soil, applied nitrogen is lost in various forms such as volatilization, denitrification, leaching and runoff out of which ammonium volatilization causes the maximum loss. The recovery of applied nitrogen, as recorded from various filed experiments in India, has been found to vary from 28 to 34% for submerged rice. The chemistry of nitrogen in submerged soil is quite interesting for this review.