Impact of land use practices on soil fertility status of dryland soils.

Abstract

: In order to assess the impact of long term land -use systems on soil fertility, a study was undertaken at Gunegal Research Farm of Central Research Institute for Dry land Agriculture, Hyderabad situated at 170 , 40’, 40.4’ N latitude and 780 , 39’, 55.7’’ E longitude and at a mean sea level of 626 m. Study revealed that there was considerable variation in the status of organic carbon, available phosphorus and potassium in soil under different land use systems. The organic carbon content in the soil across the land use systems ranged from as low as 0.103 % to as high as 1.27%. About 47 and 40% of the blocks under mono-cropping and intercropping system respectively were rated as low with respect to organic carbon (less than 0.5%) which is a measure of available nitrogen also .The blocks with medicinal plantations and forestry were rated as high (more than 0.75%) in organic carbon status. Most of the blocks under horticulture and agro-forestry were also rated as medium to high in organic carbon. The minimum available phosphorus recorded in the farm was 6.63 kg P ha -1 and the maximum content recorded was 36.43 kg P ha -1. A minimum of 86 kg K ha-1 and a maximum of 740 kg K ha-1 were recorded from the different blocks of the farm. Of the three soil fertility parameters, the available potassium content exhibited highest coefficient of variation (77% ), followed by organic carbon (38.33 % ) and available phosphorus (36.4 %). The content of DTPA-extractable Fe, Cu and Mn were recorded above the critical limits (4.5, 0.2, 2.0 ppm for Fe, Cu and Mn, respectively) in all the blocks indicating that the land use practices do not have any effect on the status of these nutrient cations . However, DTPA-extractable Zn was found above the critical limit (0.6 ppm) only in the blocks where forestry and medicinal systems were practiced and was below the critical limit in blocks continuously covered under mono-cropping.