Search

Under field plot experiment condition, the different application methods and application periods of selenium(Se)fertilizer were explored to make sure the absorption and accumulation of Se in plants and grains of rice. The results showed there were significant differences in the early and exuberant periods of rice for Se absorption and accumulation. Compared with the control, three kinds of application methods could significantly improve Se value of rice. From the effect of Se enrichment, the content of Se was in the range of 0.163～0.207 mg·kg-1 which increased by 5.8～7.6 times, within the safe range. From the way of Se enrichment, the order of better effect was: spraying Se at flowering stage treatment>application Se in soil>spraying Se at breeding period>CK. From the foliar application period of Se, the order of Se enrichment effect was spraying Se at flowering stage>breeding period>grain filling period>full heading period>CK. Exogenous inorganic and organic Se fertilizer could significantly promote the accumulation of Se in rice. Foliar spray in rice seedling and flowering stage could increase the Se containing of rice grain but not reduce the yield of rice.

In order to make sure the effect of straw decomposer accelerators on the maize straws in Northeast of China, mesh bag method was used to determine the decomposition characteristics of maize straw biomass amount and nutrition release regularity in one year. The results showed that after 100 days, decomposition rates of maize straws biomass amount were between 57.1%-64.1%. The highest decomposition rate of 64.1% was the treatment with the 3rd decomposer accelerator. The nutrition release rates of N, P and K were 35.1%-57.2%, 44.2%-59.6%,and 77.4%-89.7% at the end of period, respectively. And the 3rd decomposer accelerator treatment had a better effect on the release rate of P and K. All treatments had the same trend of organic C mineralization rate which increased with the time extending, at last the organic C min-eralization rate was between 65.3% and 69.1%. The results showed the 3rd decomposition accelerator had better effect than others.

The effect of different organic material turnover on soil structure and maize photosynthetic rate was researched in this paper. The results showed that comparing the control treatment, the soil bulk density of two treatments of shallow reversing and chiseling plow with straw returning and organic fertilizer were decreased by 0.13 g·cm-3and 0.09 g·cm-3, respectively. The application of shallow reversing and chiseling plow with straw turnover,organic fertilizer, green organic fertilizer and bio-fertilizer could reduce soil hardness, change the soil three phase state, improve the soil physics structure. Organic fertilizer and green organic fertilizer and bio-fertilizer increased the maize photosynthetic rate at trumpet period by 2.1~7.6 μmol·m-2·s-1. The transpiration rate of straw turnover and bio-fertilizer treatments was decreased by57% and 56% separately. Conductances of all treatments were lower than that of the control treatment at trumpet period. Meanwhile stomatal conductance was increased at filling stage which may lead to the decreasing CO2concentration with the reason that reducing of stomatal booster caused the lower CO2concentration. Returning of organic materials could reduce soil bulk density and com paction, make the soil three phase state having a reasonable range, improve crop photosynthetic rate, decrease the transpiration rate, especially the treatments of straw returning and organic fertilize. In short, protection tillage and organic materials returning to field play a positive role for improving soil fertility, soil physical characteristics, crop photosynthetic rate and crop yields.