Spatial and temporal trends in soil N-mineralization rates under the agroforestry systems in Bhabhar belt of Kumaun Himalaya, India

• Published in: Agroforestry systems Vol. 95; no. 8; pp. 1603 - 1617
• Main Authors: Karki, Himani, Bargali, Kiran, Bargali, S. S.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-12-2021; Springer Nature B.V
• Subjects: Agriculture; Agroforestry; Ammonification; Ammonium; Belts; Biomedical and Life Sciences; Forestry; Horticulture; Land use; Life Sciences; Mineralization; Nitrates; Nitrification; Nitrogen; Organic carbon; Organic soils; Rainy season; Seasons; Silviculture; Soil chemistry; Soil depth; Soil layers; Soil management; Soil pH; Soil surfaces; Soils; N-mineralization; Ammonification; Seasonal variation; Soil depth; Buried-bag; Agroforestry systems
• ISSN: 0167-4366; 1572-9680
• DOI: 10.1007/s10457-021-00669-9

To access the process of nitrogen mineralization in soil, the buried-bag technique was used among traditional agroforestry systems in the Bhabhar belt of Kumaun Himalaya. The present study, determined the relationship between various parameters of N-mineralization with agroforestry systems, seasons and soil depths. Season and soil depth have significantly (
p
 < 0.001) affected the process of ammonification, nitrification and net N-mineralization. The soil ammonium-N pool was comparatively higher than the nitrate-N pool. Highest amount of ammonium and nitrate-N were recorded in the agri-horticulture (AH) system, and lowest in the agri-horti-silviculture (AHS) system. Among the systems, highest amount of inorganic-N (ammonium + nitrate) was recorded during rainy season while, lowest during winter season. The highest ammonification rate (6.47 ± 1.47 mg kg
−1
 month
−1
) was observed in agri-silviculture system and lowest (5.67 ± 1.68 mg kg
−1
 month
−1
) in AHS system, while nitrification value was maximum (2.53 ± 0.40 mg kg
−1
 month
−1
) in AH system and minimum (2.23 ± 0.37 mg kg
−1
 month
−1
) in AHS system. The values of net N-mineralization were ranged from 4.03 ± 0.53 to 13.29 ± 0.44 mg kg
−1
 month
−1
. The values of inorganic-N and net N-mineralization were significantly more (
P
 < 0.01) in the surface soil layer (0–20 cm) than the subsurface layers (20–40 cm and 40–60 cm). Nitrogen mineralization was negatively correlated with the soil pH and positively correlated with soil organic carbon and total soil nitrogen. Higher rate of N-mineralization in AHS system indicated rapid turnover of nitrogen due to soil management practices and suggested that the changes in agroforestry based land-use systems alter the process of net N-mineralization, nitrification and ammonification.