Study On The Soil Improvement Technique For Waterlogged Land

Waterlogged land is a kind of cultivation land which is easily logged with water seasonally or perennially. The waterlogged land is actually agricultural wetland which is a kind of land resources used by agriculture. This research made a systematic study on waterlogged soil reclamation technology through the combined means of field trials, lab analysis, investigation and survey, and demonstrations. The research results are as follows.Waterlogged land soil has some characteristics which can be described as (1) with deep and soft soil layer resulted in easily cultivated, (2) with high groundwater level led to poor soil structure, poor water permeation, imbalance of soild-liquid-vapour ratio for the soil which has too much water and too little air and solid percentage is high in the soil, (3) with rich total soil nutrients but inadequate available nutrients, poor organic matter quality, and accumulation of reduction matter. Therefore, soil reclamation work should be done on lowering groundwater level, improving soil structure, adjusting the soild-liquid-vapour ratio, regulating cultivated soil layer and reducing reduction matter in the soil.The soil fertility geographical features showed that all parameters had some relationship from west to east and soil available K and organic matter content had significant relationship from north to south. Long term investigation result showed soil organic matter and available N content yearly decreased by 1.11 g/kg and 1.68 mg/kg, respectively. It indicated the waterlogged soil fertility has decline tendency.The physical and chemical properties of soil are significantly improved after drainage pipes were placed deep in the land, by which soil salinity was shifted downwards. However, the field trial showed that rice growth and yield were not significantly improved by the use of drainage pipes probably due to short period of the pipes placed.The general aim of land level was achieved. Nevertheless, the study showed that top soil nutrients content was decreased by a big margin after land level. The soil physical properties also damaged greatly compared with without level. So top soil treatment is a suggestion when take land level measure.Crop rotation with rice and upland crops could lower the groundwater level, improve soil aeration condition, increase soil available nutrients content, and decrease soil reduction matter content during rice planting season. Soil organic matter and available P content would decrease if fertilization was neglected, which indicated P fertilizer should be applied when upland crops planted.The treatment with left high rice straw (25-30cm) and compost application achieved good results for rice straw replacement which improved soil organic matter and physical and chemical properties as well as supplied some nutrients for rich growth. High level of mechanization is the base for cotton straw replacement to the field. It showed that replacement of cotton straw had lots of advantages such as improving soil aeration space, permeation, organic matter content, and decreasing soil density and hardness.Fertilizer inflow application method applies to the wetland paddy soil with land leveled, good irrigation condition, large population and small land, or for elderly agricultural population, and schistosomiasis area. Compared with broadcast, no other equipments except a container in which fertilizer dissolved will need for inflow application method and the fertilizer can be well-distributed in the field, so this fertilization method is suitable. It need no water drain off from the field within 5 days after inflow application. Compound fertilizer made domestic can instead of inflow fertilizer import abroad.The trials results showed that crops yield increased by 6.24 per cent with long lasting nitrogen fertilizer IBDU and by 3.09 per cent with OM compared with urea treatment. Coefficient of N utilization with IBDU increased by 14.62% and with OM increased by 8.57%, respectively. IBDU is most applicable for rice planting. In order to improve both rice...