Impact of Tree Species, Distances and Soil Depth on Nitrogen, Phosphorus, and Potassium Concentration in Different Locations

Abstract

Soil nutrient status basically the availability of nitrogen (N), phosphorus (P), and potassium (K), is a key determinant of soil fertility and growth of the tree based agroecosystems. Field research was conducted to quantify the influence of tree species, soil depth, and distance from the tree trunk on soil available nitrogen, phosphorus, and potassium across three agroclimatic zones of Haryana (Jind, Rohtak, and Jhajjar). Soil samples were collected beneath the canopy of ten tree species at four horizontal distances (0, 2, 4, and 6m) and four vertical depths (0-50, 51-80, 81-110, and 111-140cm) during sowing and harvest stages of crops using manual auger machine. Nutrient estimation was carried out using the micro-Kjeldahl method for nitrogen content, spectrophotometric determination for phosphorus content, and the chloroplatinic acid gravimetric method for potassium content. Analysis of variance showed that before and after harvesting conditions were the dominant source of variation for all nutrients, recording the highest mean square (MS) values for nitrogen (23,137.95 in Jind, 19,519.97 in Rohtak, and 20,645.39 in Jhajjar), phosphorus (56,100.22 in Jind, 219,314.67 in Rohtak, and 90,766.14 in Jhajjar), and potassium (1,449,969.30 in Jind, 2,461,823.66 in Rohtak, and 527,936.67 in Jhajjar). Soil depth and distance from the tree trunk also significantly influenced nutrient distribution, with nitrogen highest mean square value across districts, phosphorus (12,657.89) in Rohtak, and potassium (37,087.25) in Jhajjar. Tree species showed a moderate but significant influence, particularly for potassium, where the highest species related MS value was observed in Jhajjar (267,833.72). Significant interactions (T×D, E×D, and T×E×D) highlighted the multifaceted interconnection between tree species (T), environment (E), and soil distance/depth (D). The results of the present investigation showed that variations in soil N, P, and K availability are directly controlled by environmental conditions and soil depth, whereas tree species and proximity to the tree trunk regulating nutrient dynamics within agroforestry systems of Haryana.