Dynamics of soil water, salt and crop growth under farmyard manure and mulching in coastal tidal flat soil of northern Jiangsu Province

Abstract: Soil salinity, a typical characteristic of reclaimed coastal tidal flat soil, restrains soil quality improvement and crop growth seriously in coastal area of northern Jiangsu Province. Careful soil management is important for the soil salt elimination and crop promotion. Farmyard manure (FYM) and mulch applications, which affect soil properties and plant significantly, are regarded as an effective improvement pattern of saline land. As a conventional management in the study region, FYM and mulch are used for the amendment of the new reclaimed tidal flat regularly, but little is known about their effects on crop growth and the dynamic of soil water and salt. A study was conducted on a typical coastal tidal flat saline land to evaluate the effects of FYM, polyethylene film mulch (PM), straw mulch (SM), FYM combined with PM (FYM + PM), FYM combined with SM (FYM + SM) on soil water, soil salinity and crop growth in 2011 and 2012. CK represented no FYM and mulch application and served as a control. Dynamic of soil properties were observed, such as soil water content, electric conductivity (EC) and pH, and the growing indicators of maize and barley, including plant height, stem diameter, leaf area index, biomass and yield. The experiment, laid out in a randomized complete block design with three replications, was studied in Huanghaiyuan Farm, which specialized in the agricultural utilization for coastal tidal flat. Results of three continuous crop cultivations indicated that, soil water and salt fluctuated strongly and were affected by all of the treatments. Compared to the CK, all of the treatments increased soil water content, although with a quantitative difference. Soil salt, indicated by soil electric conductivity, was controlled well by PM and SM, with the relative decreasing percent of 23.91 %，28.57 %，70.28 % and 27.17 %，40.00 %，49.51 % respectively after the three harvest time. However, FYM and mulch had weak effects on soil pH. FYM application had a risk of secondary salinization because of the increased soil salt content caused by the high salt content of chicken manure; however, the increasing trend was controlled when FYM application was combined with mulch management. Growth of maize and barley were promoted significantly with high growth index and yield and kept in the order of FYM + SM > FYM + PM > FYM > SM > PM > CK. It was considered that FYM+SM was the best treatment for salinity elimination and crop promotion of the reclaimed coastal tidal flat saline land, due to the higher soil water content, lower soil electric conductivity and pH and the better plant performance under FYM+SM. Yield of maize and barley were increased significantly by FYM+SM more than 100 %, and reached the average yield of the desalted soil, which reclaimed for a long time in the study area. Therefore, the new cultivation pattern of FYM+SM is recommend for soil quality and productivity improvement of the reclaimed coastal tidal flat saline land and the sustainable utilization of FYM, crop straw in the coastal area of northern Jiangsu Province.