Effects Of Straw Mulching And Subsoiling On Soil Fertility, Groth And Grain Yield Of Summer Maize

This research was conducted in the field in Yuying Village, Pengyao Township, Xiping County, Zhumadian City, Henan Province in 2009. The research adopted four tillage patterns as follows: subsoiling and mulching, subsoiling and no mulching, no tillage and mulching, no tillage and no mulching. During the three-year-research, effects of four treatments on soil physicochemical properties, soil organic carbon, soil enzyme activities and growth and development especially the yield of summer maize were studied by field experiments and laboratory analysis. The main results indicates that:1 Effects of straw mulching and subsoiling on soil physical propertiesSubsoiling affects soil bulk density obviously. The three-year experiment suggested that subsoiling can decrease soil bulk density significantly when compared to no tillage. During seeding period and mature period, subsoiling was 0.09g/m3 and 0.07g/m3 lower than no tillage seperately on average.At 0-20cm soil layer, soil water content in mulching treatment were higher than no mulching treatments. Results of the water content showed the order of: subsoiling and mulching, no tillage and mulching, subsoiling and no mulching, no tillage and no mulching. At 20-100cm soil layer , the water content in subsoiling treatment was higher than no tillage treatments. The relevant order was: subsoiling and mulching>subsoiling and no mulching>no tillage and mulching>no tillage and no mulching.2 Effects of straw mulching and subsoiling on soil chemical propertiesIt was shown that the content of soil available N, P, K of different treatments de-creased as soil depth increased. In the seeding stage, the soil soil available N, K content under mulching treatments had a higher content than no mulching treatments; There is no significant difference between treatments. In mature stage, the soil available N, P, K content under mulching treatments had a higher content than no mulching treatments.The profile distribution of soil organic carbon (SOC), readily oxidizable carbon (ROC) and dissolved organic carbon (DOC) of diffferent treatments appeared a decline trend with depth. At 0-10 cm layer, the soil SOC, ROC and DOC content under mulching treatments were higher significantly than those of no mulching treatments. Beginning at 10-20 cm, all the three decrease rapidly under no tillage and mulching treatment. Moreover, at 20-40cm, the three kind carbon content of soil under subsoiling was significantly more than those under no tillage.3 Effects of straw mulching and subsoiling on soil biological propertiesIn terms of different treatments, the activities of soil urease, soil alkaline phosphate enzyme, soil invertase,soil catalase increased with soil depth. Along with maize growth period varies, all the activities of the four kind of enzymes showed regular changes. At 0-10cm layer, the soil enzymes activities under mulching treatments were higher significantly than those of no mulching treatments. At 10-20cm,the activities of enzymes in no tillage treatment decreased sharply. And at 20-30cm and 30-40cm, soil enzyme activities in subsoiling treatments were higher significantly compared with no tillage treatments.4 Effects of straw mulching and subsoiling on maize growth and physiological characteristicsThe research found that straw mulching have a significant influence on maize emergency. The emergency rate in mulching treament is lower than no mulching treatment. Under the treatment of no tillage and no mulching, the emergency rate increased by 2.09%, 3.72%, 5.85% seperately when compared with subsoiling and no mulching, no tillage and mulching and subsoiling and mulching .In terms of leaf area index and dry matter accumulation,four treatments were arranged: subsoiling and mulching> subsoiling and no mulching > no tillage and mul-ching >no tillage and no mulching. During mature period, dry matter were distributed in grain most. Different economic coefficient in different treatments follow the law: subsoiling and mulching> subsoiling and no mulching > no tillage and mulch-ing >no tillage and no mulching.In comparison with other treatments,subsoiling and mulching can delay maize senescence, strongthen its resistence. In comparison with other treatments, no tillage increasesd the amount of SOD, POD activities of ear leaves after flowering, followed by subsoiling and no mulching. No tillage and no mulching ranked last. After flowering, the MDA content of ear leaves increased rapidly. As the index is concerned, no tillage and no mulching has more MDA content than others, while the index of subsoiling and mulching was lowest. Correlation analysis showed that there were significant correlation between enzyme activities and MDA content of ear leaves and maize yield.The photosynthetic pigment content, Pn, PSII, Fv/Fm, qP were gradually decreases, NqP gradually increase. Correlation analysis denominated that except flowering period, there were significant or very significant correlation between Pn, PSII, Fv/Fm, qP,NqP and maize yield.5 Effects of different treatments on yield and water use efficiency (WUE) of summer maize in summer maize fieldsUnder the treatment of subsoiling and mulching, kernel rows, row grains and weight per 1000 seeds are more than those of other treatments. The yield of subsoiling and mulching increased by 6.08%, 11.51%, 21.10% when compared with subsoil-ing and no mulching,no tillage and mulching and subsoiling and no mulching. And the differences were regarded as significant.Water use efficiency has bigger difference in different treatments. The Water use efficiency of subsoiling and mulching increased 4.87%, 11.42%, 22.20% than sobsoiling and no tillage,no tillage and mulching,no tillage and no mulching.