No abstract

Field experiments were conducted in acidic soils of Mangalpur and Fulbari VDCs in western Chitwan, Nepal to study the effects of different land use systems on soil properties. Seven land use systems (cereal based lowland, cereal based upland, vegetable farm land, fruit orchard land, pasture land, forest land and farmer's field) were used and they were replicated four times in randomized complete block designs. Composite soil samples were collected from each study sites and were analyzed in laboratory for soil physicochemical properties. The data obtained were analyzed using MSTAT-C. Soil properties were significantly affected by land use systems in western Chitwan condition. Soil organic matter and total soil nitrogen were significantly higher from pasture land (4.69 % and 0.23 %) and the lowest were from farmer's field (2.40 % and 0.08 %). However, available soil phosphorous content was significantly higher from cereal based upland (448.3 kg ha -1 ) and it was the lowest from forest land (13.0 kg ha -1 ). Soil bulk density and pH were not significantly affected by land use systems. Since land use systems and management practices significantly affect soil physical and chemical properties, an appropriate and sustainable land use management option is necessary for fertile and healthy soil. Conservation tillage with the addition of sufficient organic inputs can be suggested based on this study to maintain soil health for sustained production and optimum activity of soil organisms under the western Chitwan land use systems.

Nutrient use efficiency is crucial for increasing crop yield and quality while reducing fertilizer inputs and minimizing environmental damage. The experiments were carried out in silty clay loam soil of Lalitpur, Nepal, to examine how different amounts of nitrogen (N), phosphorus (P), and potassium (K) influenced crop performance and nutrient efficiency indices in wheat during 2019/20 and 2020/21. The field experiment comprised three factorial randomized complete block designs that were replicated three times. N levels (100, 125, 150 N kg ha-1), P levels (25, 50, 75 P2O5 kg ha-1), and K levels (25, 50, 75 K2O kg ha-1) were three factors evaluated, with a total of 27 treatment combinations. Grain yields were significantly increased by N and K levels and were optimum @ 125 kg N ha-1 and @ 50 kg K2O ha-1 with grain yields of 6.33 t ha-1 and 6.30 t ha-1, respectively. Nutrient levels influenced statistically partial factor productivity, internal efficiency, partial nutrient budget, recovery efficiency, agronomic efficiency, and physiological efficiency of NPK for wheat. Nutrient efficiency was found to be higher at lower doses of their respective nutrients. Higher P and K fertilizer rates enhanced wheat N efficiencies, and the case was relevant for P and K efficiencies as well. Wheat was more responsive to N and K fertilizer, and a lower rate of P application reduced N and K fertilizer efficiency. This study recommends to use N @ 125 kg ha-1, P2O5 @ 25 kg ha-1 and K2O @ 50 kg ha-1 as an optimum rate for efficient nutrient management in wheat in mid-hills of Nepal.

No abstract

Summary ± ZusammenfassungThe rice-wheat annual double cropping system occupies some 0.5 million ha in the Himalayan foothills of Nepal. Alternating soil drying and wetting cycles characterize the 6±10 weeks long dry-to-wet season transition period (DWT) after wheat harvesting and before wetland rice transplanting. Mineral fertilizer use in the predominant smallholder agriculture is low and crops rely largely on native soil N for their nutrition. Changes in soil aeration status during DWT are likely to stimulate soil N losses. The effect of management options that avoid the nitrate buildup in soils during DWT by N immobilization in plant or microbial biomass was studied under controlled conditions in a greenhouse (2001/2002) and validated under field conditions in Nepal in 2002. In potted soil in the greenhouse, the gradual increase in soil moisture resulted in a nitrate N peak of 20 mg (kg soil) ±1 that rapidly declined as soil moisture levels exceeded 40 % water-filled pore space (equiv. 75 % field capacity). Similarly, the maximum soil nitrate build-up of 40 kg N ha ±1 under field conditions was followed by its near complete disappearance with soil moisture levels exceeding 46 % water-filled pore space at the onset of the monsoon rains. Incorporation of wheat straw and/or N uptake by green manure crops reduced nitrate accumulation in the soil to < 5 mg N kg ±1 in pots and < 30 kg N ha ±1 in the field (temporary N immobilization), thus reducing the risk for N losses to occur. This ªsavedº N benefited the subsequent crop of lowland rice with increases in N accumulation from 130 mg pot ±1 (bare soil) to 185 mg pot ±1 (green manure plus wheat straw) and corresponding grain yield increases from 1.7 Mg ha ±1 to 3.6 Mg ha ±1 in the field. While benefits from improved soil N management on lowland rice are obvious, possible carry-over effects on wheat and the feasibility of proposed options at the farm level require further studies. . Mögliche residuelle Effekte auf die Folgefrucht sowie die Machbarkeit der vorgeschlagenen Optionen in unterschiedlichen Anbausituationen erfordern weitere Untersuchungen. Beeinflussung der Dynamik des Bodenstickstoffs in Reis-Weizen-Rotationen Nepals