Effect of hillslope positions and soil properties on soil micronutrient availability in steep terraced croplands of north-western Himalayas

Soil micronutrients are critical for plant growth and reproductive processes to complete their key functionality of the life cycle. The availability of micronutrients in hilly and mountainous regions is influenced by topography-controlled soil processes at various hillslope positions. However, the ruggedness of terrains makes it challenging to gather comprehensive data on soil micronutrient status, which in turn limits effective micronutrient management. This issue is particularly significant to the acidic soils of the North-western Himalayas, where agriculture is the primary source of livelihood. Therefore, this study was designed to explore the availability and variability of major micronutrients (Zn, Cu, Fe, and Mn) in the soils of hilly and mountainous landscapes across five different hillslope positions and various cropping systems, and to examine their relationship with physico-chemical properties of soils. The study revealed that all micronutrients were present in sufficient quantities across the hillslope positions. However, a slight tendency toward zinc deficiency was observed at some hillslope positions. Principal component analysis (PCA) highlighted the importance of micronutrients Fe, Mn, Zn, and Cu to pH, organic matter, sand and silt contents in the landscape. It revealed that pH and organic matter were critical factors influencing micronutrient availability, with higher levels of organic matter generally enhancing the availability of these micronutrients. The study further concluded that a complex interplay of topography, soil management practices, and cropping systems influence soil micronutrient availability. The variability observed at the hillslope scale highlights the need for site-specific management approaches. Understanding these factors is crucial for optimizing soil micronutrient management and ensuring sustainable agricultural productivity in the soil erosion-prone fragile Himalayan region.