Pramila AggarwalMUKHTAR AHMED2016-09-232016-09-232012http://krishikosh.egranth.ac.in/handle/1/78631A study was conducted in farmers‘ fields of Rai block of Sonepat district to study the long term impact of two widely adopted resource conservation technologies (RCT‘s) namely bed planting and zero tillage on structural properties of soils of recent alluvial plains of river Yamuna. Vegetables growing bed planted areas mostly had medium texture soils, easy access to market and availability of fresh water. Zero tillage was practiced mainly by farmers to timely sow wheat in fine textured soils and low lying areas where soils do not dry even in mid-November. Aggregate mean weight diameter by dry sieving and wet sieving (DS-MWD and WS-MWD) under different RCT‘s were studied to compare structural condition of the soils under continuous use of these technologies. Other important structural indices such as dispersion ratio (a measure of ease of dispersion) (DR), colloid moisture equivalent ration (a measure of ease of percolation) (CMER), erosion ratio (EI), stability index (SI), clay ratio (CR) were also studied to monitor the susceptibility of soil to erosion. Results revealed that in the surveyed villages under conventional tillage, the average magnitude of DR and ER were 0.58 and 0.82, respectively, and CMER was <1, which indicated the erodible nature of these soils. Analysis of data of bed and conventional systems revealed that on an average, there was 0.07-0.08% increase in OC in bed planted system as compared to conventional system. It was mainly due to fewer disturbances in soil because of reshaping of beds for next two seasons before making fresh beds. Improved soil OC in bed system increased WS-MWD (1.89 mm) as compared to CT (1.57 mm). On the other hand, DS-MWD of bed system was lower than that of CT. Therefore CMWD was lower in beds as compared to CT, which indicated improvement in aggregate stability by adoption of bed planting system. The decrease of DR, ER and CR from 0.66, 0.52 and 4.25under CT to 0.42, 0.28 and 2.38 under beds indicated reduced eroding tendency of these soils under bed planting. Similarly increase in CMER and SI from 0.75 and 20.2 under CT to 1.1 and 34 under bed also indicated improvement in soil structural condition by bed planting. Comparison of soil data of ZT and CT showed improvement in OC, AWC and 28 reduction in BD and PR under ZT as compared to CT. Improved soil OC in ZT increased WS-MWD (mm) as compared to CT (mm). The decrease of DR, ER and CR from 0.74, 0.63 and 5.99 under CT to 0.6, 0.46 and 3.8 under ZT indicated improved aggregation under zero tillage. Similarly increase in CMER and SI from 0.66 and 9.21 under CT to 0.7 and 20.4 under ZT also indicated improved soil structural condition by adoption of zero tillage. Thus in nutshell it was concluded that by adopting suitable RCT‘s soil carbon and aggregation were improved and soils became more resistant to erosion.Thesis