Evaluating Soil Nutrient Status of Mandarin Orchards across Varied Altitudes in Gorkha, Nepal

Abstract

Mandarin, a prominent crop in Nepal, exhibits remarkable adaptability to different altitudes, resulting in diverse soil and nutrient conditions in orchards. Understanding these variations is crucial for optimizing orchard management practices and ensuring sustainable fruit production. This research endeavor sought to assess the nutritional profile of the soil in mandarin positioned at diverse elevations in Gorkha district, Nepal. The orchards were classified into five elevation groups: 800 masl, 900 masl, 1000 masl, 1100 masl, and 1200 masl. Using randomized complete block design (RCBD), each altitude contained ten composite soil samples, and was then subjected to chemical analysis to assess their properties. The results showed that soil pH increased with altitude, with the highest pH (6.66±0.045) and soil organic matter (OM) (5.88±0.12%) at 1200 masl and the lowest pH (5.5±0.045) and OM (1.92±0.12%) at 800 masl. Soil acidity was observed 5.79±0.045 at 900 masl and 5.5±0.045 at 800 masl, while all other altitudes had neutral soils. Nitrogen content followed a
similar trend, with the highest at 1200 masl (0.32±0.007%) and the lowest at 800 masl (0.10±0.007%). Phosphorus and potassium showed no significant variation with altitude. Available phosphorus was the highest at 1000 masl (72.93±2.02 kg ha^-1) and the lowest at 800 masl
(51.61±2.02 kg ha^-1). Maximum available potassium (365.34±6.84 kg ha^-1) was observed at 1100 masl, while the minimum (337.63±6.84 kg ha^-1) was recorded at 800 masl. In 18% of the samples, nitrogen exhibited the lowest concentration, while phosphorus was limiting in 12% of the samples. Potassium was not found to be a limiting nutrient in any of the samples. Variations in soil pH, OM, and nutrient content call for altitude-specific nutrient management to optimize mandarin production. Further studies are required in diverse ecology to characterize nutrient requirements and enhance sustainable mandarin cultivation practices.