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Soil plays a critical role as the primary reservoir of phosphorus (P) in terrestrial ecosystems. Sequential fractionation has been extensively utilized to gain insights into the characteristics and dynamics of soil P. However, there is a knowledge gap regarding the different P pools in Nepalese soils. Therefore, this study aimed to investigate the impact of cropping systems on soil P fractions in the central mid-hills of Nepal. The study focused on four cropping systems: vegetable, fruit, rice, and maize-based systems, which exhibited variations in nutrient management, topography, and cropping intensity. A total of 240 soil samples (60 samples from each cropping system) were collected from multiple sites within the central mid-hill region. Standard analytical methods were used to determine the general parameters of the soils, while the sequential fractionation method was employed to assess the organic and inorganic P pools. The results indicated that the effect of cropping systems on soil pH, calcium carbonate (CaCO3) content, and the proportion of sand, silt, and clay was not statistically significant in terms of general parameters. However, significant differences were observed among the different cropping systems in organic matter (OM), electrical conductivity (EC), cation exchange capacity (CEC), and available phosphorus. Similarly, in terms of inorganic phosphorus fractions, loosely bound P (LB-P), aluminum bound P (Al-P), iron bound P (Fe-P), and reductant soluble P (RS-P) were significantly affected, while calcium bound P (Ca-P) did not show a significant difference. Furthermore, in terms of organic phosphorus fractions, labile organic P (L-Po), fluvic acid organic P (FA-Po), and non-labile organic P (NL-Po) exhibited significant differences, whereas moderately labile organic P (ML-Po) and humic acid organic P (HA-Po) did not show a significant difference. Additionally, reductant soluble P showed a significant difference, while total P did not differ significantly. The vegetable-based system exhibited higher levels of the majority of P fractions, followed by the fruit-based, maize-based, and rice-based systems. These findings emphasize the importance of considering cropping systems and their response to different phosphorus pools, as this knowledge can contribute to the development of improved soil phosphorus management strategies and promote sustainable agricultural practices in the region. [ABSTRACT FROM AUTHOR]

Effective management of nitrogen (N), phosphorus (P), and potassium (K) are crucial for increasing crop production and productivity as they are associated with a number of enzymatic and physiological activities in wheat (Triticum aestivum L.). Field experiments were carried out during the winters of 2019˗˗20 and 2020˗˗21 to study the influence of varying levels of N, P, and K on crop performance, nutrient concentration, and uptake at various growth stages of wheat in mid-hill of Nepal. The study was conducted with factorial combinations of three N levels (100, 125, and 150 kg N ha−1), three P levels (25, 50, and 75 kg P2O5 ha−1) and three K levels (25, 50, and 75 kg K2O ha−1) in a randomized complete block design with three replications. Increasing N and K rates significantly (p <.05) increased total dry matter, grain yield, nutrient concentrations and uptakes in wheat. Pooled means showed significantly higher grain yields of 6.3 t ha−1 were obtained with N @ 125 kg ha−1, and K2O @ 50 kg ha−1 than lower rates. At maturity, average concentrations of N, P, and K in grain were 15.5, 3.6, and 5.8 g kg−1, respectively, and 5.4, 0.9, and 10.9 g kg−1 in straw, respectively, depending on the rate of NPK applied. N and P were mostly accumulated in wheat grain, whereas K was found higher in wheat straw than in grain. The nutrient concentration values of grain and straw can be used as a reference for determining nutrient removal from soil using a yield-based technique in wheat. [ABSTRACT FROM AUTHOR]

Field experiments were conducted to investigate the effect of various levels of nitrogen, phosphorus, and potassium on the nutrient content of maize grain and stover and their uptake at different growth stages of hybrid maize in silty clay loam soil of Khumaltar, Lalitpur, Nepal, during summer of 2019 and 2020. Experiment was carried out in three factorial randomized complete block design with a total of 27 treatment combinations and replicated 3 times. Three factors were three levels of nitrogen (150, 180, and 210 N kg/ha), phosphorus (40, 60, and 80 P2O5 kg/ha), and potassium (40, 60, and 80 K2O kg/ha). Increasing nitrogen and potassium rates significantly (p <.05) increased total dry matter, grain yield, nutrient concentration, and accumulation of NPK in maize. On average, application of a higher rate of nitrogen (210 kg/ha) and potassium (80 kg/ha) produced grain yields of 10.95 t/ha and 10.54 t/ha, respectively, indicating higher uptake and higher grain yield. The average concentrations of N, P2O5, and K2O were 15.79, 9.56, and 3.77 g/kg in grain and 6.74, 4.17, and 10.46 g/kg in stover at maturity differentiated depending upon the rate of NPK applied. Nitrogen and phosphorus were accumulated mostly in grain (68–83%), whereas potassium was observed more in stover (64–77%). On average, 9.97 tons of maize grain removed 282.81 kg NPK/ha with a positive linear regression (R2) value of 0.89. The reference value of nutrient contents in maize crop obtained from this study can be used to estimate the time and amount of NPK removed from soil for better nutrient management. [ABSTRACT FROM AUTHOR]