Impact of seasonal variations and cropping systems on soil microbial biomass and enzymatic activities in slope gradient moisture stressed soils of Punjab-Pakistan

Soil biological health is one of the best indicators for soil fertility thus plays a significant role in sustainability of cropping systems. This study was designed to investigate the impact of different seasonal variations and cropping systems on soil microbial biomass and enzymatic activities in sloppy arid soils. Soil samples were collected from the sloppy soils (high, medium and low height terraces) of Khairimurat areas under wheat (Triticum aestivum)–millet (Pennisetum glaucum) and wheat (Triticum aestivum)–mung bean (Vigna radiate) cropping systems. The results revealed that the soil microbial biomass Carbon (Cmic), Nitrogen (Nmic), Phosphorous (Pmic), soil enzymes such as Dehydrogenase (DH) and Alkaline Phosphatase (AP) activity entirely depends on the soil water availability under both cropping systems at all height terraces. The wheat-mung bean cropping systems stored relatively more Nmic, Pmic, AP (activity) and less Cmic, DH (activity) as compared to wheat-millet cropping systems. Regarding the slope gradient under both cropping patterns, high height terraces had retained more Cmic contents, medium height terraces had shown more DH activity and low height terraces had maintained more Pmic contents. In addition to this, Nmic contents and AP activity remained almost similar in all types of terraces under both cropping patterns. Pertaining to seasonal variations under both cropping patterns, the summer season had shown more Cmic, Nmic, Pmic, DH and AP activity as compared to spring, winter and autumn season in all types of terraces. The soil water contents increased down to depth in all types of terraces under both cropping patterns. However, soil water contents remained heterogeneous in all types of terraces under both cropping patterns. In conclusion, it is suggested that in arid environments, cover crops be included in cropping system in order to enhance soil biological health.