Changes in Soil Properties in Hot Arid Region of India

Changes in status of soil organic carbon (SOC), phosphorus, potassium, pH, EC and bulk density after an interval of about three decades were re-evaluated in the year 2002 in the soils (0–1.0 m deep) of a part of arid ecosystem dominantly under pearl millet (pm)-pearl millet (pm) cropping sequence and under alternate land use systems. Observations revealed that the SOC available phosphorus and potassium stock was depleted by 10.4, 21.5 and 17.6% respectively under pm-pm sequence. Soil pH exhibited a notable increase in the irrigated system of agriculture, while difference in bulk density was inconclusive. Depletion of soil organic carbon and available potassium depletion was highest in the sandy soils, followed by coarse loamy soils, while phosphorus reduction was highest in the loamy-skeletal soils. Remarkably good management practices in Bhagasani soils enhanced the SOC and available phosphorus, whereas Pipar soils sustained the SOC level of 1975. Pm-pm sequence in the arid Rajasthan led to a rise in the thickness of overburden sand in Kolu and Bap soils, while loss of topsoils was conspicuous in Bap variant and Soila series. In contrast, alternate lands use systems namely silvipasture, silviculture and agroforestry on coarse loamy soils (Pal series) maintained 70.8, 101.0 and 58.4% higher SOC than the similar soils used for pm-pm sequence at the farmers field. Soil pH and available potassium concentration were unaffected in latter! Extent of fallowing, stability of aggregates and initial SOC concentration, period of canopy cover and level of management alone or their permutations governed the variations within and between the land use systems.