Impact of long-term organic farming on soil quality
Loading...
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Punjab Agricultural University, Ludhiana
Abstract
The intensive cropping coupled with the continuous use of chemicals as inputs has resulted in various issues including declining soil physical environment and productivity. Organic farming plays a crucial role in improving soil quality by excluding the use of synthetic fertilizers and chemicals. The present study was thus conducted on the impact of long-term (12 years) organic farming on soil quality under different cropping systems in a sandy loam. Soil samples were collected from organic and chemical plots for each cropping system viz green manure (GM)-basmati rice-wheat, GM-basmati rice-gram, soybean-wheat and summer moong-cluster bean-wheat from 0-15 and 15-30 cm soil depths for analyzing physical and chemical parameters, whereas surface soil layer (0-15 cm) was analyzed for biological parameters after harvest of kharif and rabi crops. The study revealed that mean bulk density was lower in organic farming by 7.64 and 3.65 percent in 0-15 and 15-30 cm soil layer, however total soil porosity was higher in organically managed soils in both the soil layers. The mean maximum water holding capacity (MWHC), mean weight diameter (MWD), saturated hydraulic conductivity, steady state infiltration of soil was higher by 42.3, 64.5, 60.7 and 60 per cent under organic farming than in soil under chemical farming. The moisture retention in soils under organic farming increased from 5.17 to 10.3 and 5.46 to 18.6 per cent in surface and sub surface soil layer, respectively compared to chemical farming. No significant difference in the pH of organic (6.96) and chemically (7.22) managed soil was observed. Electrical conductivity of soils of chemical plots (0.17 dS m-1) was higher than in the organic plots (0.14 dSm-1). The soil organic carbon, cation exchange capacity, available P, K and DTPA-micronutrients (Fe, Zn,Mn and Cu) were significantly higher in organic plots than in chemical plots. The dehydrogenase and alkaline phosphatase were higher in soils under organic farming, however urease enzyme was higher in chemical farming. Soil microbial population especially the bacterial, fungal and actinomycetes counts, water soluble carbon and carbohydrate carbon was higher in organic farming plots. Soil physical, chemical and biological parameters were observed to be highest in GM-basmati rice-wheat and lowest in soybean-wheat cropping system. The soil quality index (SQI) of organic farming was better than the chemical farming. Principal component analysis revealed that soil properties were highly correlated with organic farming and GM-basmati rice-wheat cropping system. Mean weight diameter, cation exchange capacity and soil respiration was best soil indicator by principal component analysis.