EVALUATION OF SOIL PRODUCTIVITY UNDER DIFFERENT CROPPING PATTERNS ON SLOPPY LANDS (TERRACES) IN POTHOWAR

Abstract

Rainfed areas in general and Pothowar region in particular have great potential to meet the grain need of the country but there are certain limitations which affect the crop productivity on these areas. These include erratic rainfall, depletion of plant nutrients by soil erosion, low soil organic matter content, soil compaction on non- sloppy lands and ultimately poor soil moisture availability for crop production. The limitations can be minimized/overcome by the adoption of soil management practices such as soil conservation measures, tillage practices and reducing slopes through terracing. The sloppy lands have been converted into various types of terraces such as bench terraces and broad base terraces on which different cropping patterns are being practiced by the farmers. These patterns include Wheat-Maize and Wheat-Maize (Fodder) in Kahuta (high rainfall) area, Wheat-Millet-Fallow and Wheat-Millet-Lentil in Khairimurat (medium rainfall) area and Wheat-Fallow and Fallow-Groundnut in Pindi Gheb (low rainfall) area. The crops included in these patterns have more crop water requirement and if the drought prevails, the yields of these crops will be significantly affected. This study was conducted in two different stages. In the first stage, monitoring and evaluation work was carried out and in the second stage field experiments were performed at the selected sites to test the suitability of new cropping patterns. During survey work, experimental site were selected and soil samples were collected from these sites for the evaluation of soil fertility status, soil moisture variation throughout the year, soil microbial biomass in various seasons. In addition to this, crop yields during Rabi and Kharif seasons were recorded. The climatic data on rainfall and temperature were obtained from the meteorological department. Fertilizer application and management practices adopted by the farmer were also recorded. The collected soil samples were subjected to analyses for physico-chemical properties such as particle size analysis (soil texture), soil moisture release curve, electrical conductivity (ECe), pH of the saturated soil paste (pHs), calcareousness (CaCO3), cation exchange capacity (CEC), total organic carbon (TOC), total nitrogen, soil sodium (Na+), available potassium (K+), calcium plus magnesium (Ca+2+Mg+2), microbial biomass carbon (Cmic), microbial biomass nitrogen (Nmic) and soil enzymes (Alkaline Phosphatase and Dehydrogenase). The results showed that in September 2007, more average soil water content was available in high and medium terraces under Wheat-Miaze and Wheat-Maize (as fodder) cropping pattern in Kahuta area, in high and low terraces under Wheat-Millet- Fallow and Wheat-Millet-Lentil cropping pattern in Khairimurat and under Wheat- Fallow and Fallow-Groundnut in Pindi Gheb areas respectively. The pysico-chemical characteristics of all the sites showed that the texture of soil was sandy loam under Wheat-Maize cropping pattern, sandy clay loam under Wheat-Maize (Fodder) cropping pattern in Kahuta area, loam under Wheat-Millet- Fallow and Wheat-Millet-Lentil cropping patterns in Khairimurat area and sandy clay loam under Wheat-Fallow and Fallow-Groundnut cropping pattern in Pindi Gheb area. The results of all sites indicated that the soil was alkaline, calcareous in nature, non- saline, non-sodic, having marginal total organic carbon, total nitrogen, adequate available soil potassium but deficient in available soil phosphorus. The bench terraces of Kahuta area had more soil fertility on the low height terraces and broad base terraces of Khairimurat and Pindi Gheb area had more soil fertility on the upper and medium height terraces. The soil water release curve indicated that Dhok Tarhan soils had more plant water availability as compared to the Jagiot Khalsa, Dhupri and Kasran sites. Incubation study was conducted in the laboratory to evaluate the rate of mineralization of different organic substrates in different soil textures. The treatments tested were viz. 1) control, 2) Groundnut straw and 3) Wheat Straw (1% on soil weight basis). Soil samples were taken after 2, 4, 7, 14, 28 and 60 days for the determination of Cmic, Nmic, Pmic, DH and AP. Completely Randomized Design (CRD) along with three replications was used for this study. This study revealed that high rate of mineralization of organic amendments was on 28 days after incubation under controlled condition under various textured soils of Kahuta, Khairimurat and Pindi Gheb areas. This study indicated that incorporated groundnut straw mineralized after one month in the field for the availability of nutrients to the crops. In the second part of the study, field experiments were carried out at Kahuta, Khairimurat and Pindi Gheb areas. The existing cropping patterns were Wheat-Maize and Wheat-Maize as Fodder in Kahuta, Wheat-Millet-Lentil and Wheat-Millet-Lentil in Khairimurat and Wheat-Fallow and Fallow-Groundnut in Pindi Gheb area. In these experiments, the high kharief water requirement crops such as Maize and Millet were replaced with Mungbean having low water requirement. The modified cropping patterns viz Wheat-Mungbean at both sites in Kahuta, Wheat-Mungbean-Fallow and Wheat-Mungbean-Lentil in Khairimurat and Wheat-Mungbean and Fallow-Groundnut in Pindi Gheb area were tested. The data showed that the modified cropping patterns Gheb areas. This study indicated that incorporated groundnut straw mineralized after one month in the field for the availability of nutrients to the crops. In the second part of the study, field experiments were carried out at Kahuta, Khairimurat and Pindi Gheb areas. The existing cropping patterns were Wheat-Maize and Wheat-Maize as Fodder in Kahuta, Wheat-Millet-Lentil and Wheat-Millet-Lentil in Khairimurat and Wheat-Fallow and Fallow-Groundnut in Pindi Gheb area. In these experiments, the high kharief water requirement crops such as Maize and Millet were replaced with Mungbean having low water requirement. The modified cropping patterns viz Wheat-Mungbean at both sites in Kahuta, Wheat-Mungbean-Fallow and Wheat-Mungbean-Lentil in Khairimurat and Wheat-Mungbean and Fallow-Groundnut in Pindi Gheb area were tested. The data showed that the modified cropping patterns