Saturday, 15 July 2006
150-7

Productivity and Soil Quality as Affected by Fencing in Mixed Mub-catchment in North-east Tract of Punjab, India.

M. S. Hadda, Dept of Soils, Punjab Agricultural Univ, Ludhiana, 141004, India and K. B. Thapa, Dept of Soils, Punjab Agricultural Univ, Ludhiana, 141004, India.

The increase in human and cattle population, decrease in size of land holdings have resulted in indiscriminate cutting of trees, removal of bushes, grazing, browsing and trampling activities in the north–east tract of Punjab, India. Such interventions affect soil physical and chemical properties and productivity. Thus, site-specific investigations are needed to identify a few key variables or combination of variables for designing strategies for suitable soil management. Keeping these points in view, present study was carried out with the objectives i) to assess soil productivity in relation with soil physical and chemical parameters ii) to group measured soil data into few principal components to explain variability. The study was conducted in mixed sub-catchment at Zonal Research Station for Kandi Area (ZRSKA), Ballowal-Saunkhari in district NawanShahr of Punjab, India. The main treatments (2) imposed were fenced and no fenced. These were replicated thrice in factorial randomized block design. Since the soil depth can be influenced by genetic factors and severity of past soil erosion, the sites were selected within the same parent and landscape unit. The bulk and core soil samples were collected from 0-5, 5-10, 10-15 and 15-30 cm depths from each replication . The soil samples were analyzed for their soil chemical and physical attributes. The parameters related with productivity were: penetration resistance, geometric mean weight diameter and organic C content. Under fenced treatment,76% of the total variance was explained by first two principal components (PCs). The PC1 explained 46 % of the total variance in which 10 chemical parameters had significant loadings. The organic carbon, cation exchange capacity (CEC), available potassium, total nitrogen, available phosphorus, citric acid soluble phosphorus and exchangeable calcium were positively weighted. The pH, exchangeable magnesium and citric acid soluble potassium were negatively weighted. The rotated scores of PC1, deceased in order: organic carbon (43) = CEC (43) = available potassium (43 > total nitrogen (42) > available phosphorus (30) > citric acid soluble phosphorus (19) > exchangeable calcium (2). The organic carbon, cation exchange capacity (CEC), available potassium, total nitrogen, available phosphorus, citric acid soluble phosphorus and exchangeable calcium were positively weighted. The pH, exchangeable magnesium and citric acid soluble potassium were negatively weighted. Under the same treatment, the 80 % of the total variance was explained by first three PCs for soil physical properties. The principal component one (PC1), principal component two (PC2) and principal component three (PC3) explained 54, 14, and 12 % of the total variance, respectively. The other positively weighted soil parameters were penetration resistance, sand and bulk density whereas saturated hydraulic conductivity, clay, gravel, water holding capacity, available water, silt, total porosity, mean weight diameter of soil aggregates were negatively weighted. Under no fenced treatment, 73 % of the variance was explained by first three principal components (PCs) for chemical parameters. The PC1 explained 43 % of the total variance in which 10 chemical parameters had significant loadings. The organic, CEC, available potassium, total nitrogen, citric acid soluble phosphorus and exchangeable magnesium were positively weighted. The other soil parameters observed to be negatively weighted were available phosphorus; exchangeable calcium, pH and citric acid soluble potassium. The rotated scores of PC1 decreased in order: available potassium (41) > organic carbon (38) > CEC (35) > total nitrogen (33) > citric acid soluble phosphorus (26) > exchangeable magnesium (7). Similarly under the same treatment, the soil physical parameters, explained 77 % of the total variance by first three PCs. The PC1 explained 41 % of the total variance, where 12 physical parameters had significant loadings. The penetration resistance, sand, bulk density and silt were positively weighted whereas gravel, water holding capacity, saturated hydraulic conductivity, clay, plant available water, total porosity, geometric mean weight diameter and mean weight diameter of soil aggregates were negatively weighted. The rotated scores of PC1 decreased in the order: penetration resistance (42) > bulk density (26) > sand (14) > silt (1).


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