| In northeast of China farmers have formed the habit of ridge tillage for corn. In order to achieve the requirements for agricultural machinery operation, straw were all removed from the field or burt in situ. In addition, people used the abundant chemical fertilizer instead of farmyard manure. Long-term predatory operation caused serious soil degradation. In order to reconstruction of the black soil fertility, it is a key method to add the input of organic matter in soil. Therefore, it is considerable important to study the application of conservation tillage technology, which help us realize the reconstruction mechanism of soil organic matter.We conducted the experiments in Conservation Tillage Research and Development Base (43°19’N,124°14’E) of Chinese Academy of Sciences in Jilin province from2007to2012. The treatments were set as no-tillage (NT-0), no-tillage with stalk cover (NTS,NT-33/67/100) and ridge tillage (RT). The soil moisture, soil temperature, bulk density, field earthworm population, soil organic matter in different sampling depths and plant biomass were all measured. We also determined the content of soil organic carbon and amino sugars in soil particle size fractions (0-2cm,2-5cm,5-10cm,10-20cm). The results were as follows:1. The soil water content increased in the treatment of NTS(NT-33/67/100) compared with in the treatment of RT. However, the soil temperature, at5cm depth of soil, the NT-100was lower in the treatment of NTS than that in the treatment of RT.2. The soil bulk density increased in the treatment of NT, ranged from1.24to1.40g cm-3. There was no significant change for the number of earthworms in treatment of RT and NT-0. However, the treatment of NT-100increased the number and quality of earthworms (p<0.05).3. The results showed that NTSinhibitedthe corn growth. Before the flowering period, NTS significantly reduced maize plant height, leaf area index and dry matter accumulation, this kind of influence increased with the amount of straw mulching. It is no affect of NT-0for maize plant height, leaf area index and dry matter accumulation. In different growth period, the leaf area index in NT-0is significantly slower than RT. NTSyeild is mainly caused by the decrease in the number of effective ears at harvest time. No-till had smalleffect on the theoryyield,The100-weight of the corn is more than that of RT. So, the field management should be strengthened, the quality of agricultural machinery should be improved. It is helpful for the popularize no-till in the Northeast.4. The results showed that NTS improved the soil organic carbon content. The accumulation of organic carbon has obvious enrichment. The amount changed with the increased amount of straw mulching. In the surface layer0-2cm, NTS(NT-100/67/33)increased soil organic carbon content:29.7%,17.9%and11.5%,4.0%,5.1%and2.8%at2-5cm in the past five years. The NT-0has little change in soil organic carbon content compared with RT. It has little effect that only changecultivation method without straw mulching in the short term.5. NTS promoted the accumulation of soil amino sugars in the top soil (0-2cm) compared with NT-0. The amounts of amino sugars derived from different fungi and bacteria changes significantly under the stover mulching, the amounts of glucosamine and galactosamine increased with stover mulching quantity increased, while muramic acid was significantly increased only under100%stover mulching. Furthermore, the ratios of glucosamine to muramic acid in stover mulching treatments were higher than that of in no stover mulching treatment. It suggests that the fungi play a dominant role in stover mulching agroecosystems as the enrichment of fungal-derived glucosamine, thus leading to higher soil organic C storage in the soils.6. Although the implementation of the no-till has no obvious impacts on fraction of soil, impacts the organic carbon content. In the surface layer (0-5cm), NTS enhances the clay adsorption ability of organic carbon. The adsorption capacity showed increased with stover mulching quantity increased. NTS also increases the storage capacity of clay. In addition, the Enrichment of clay were>1, in the layer of0-2cm the Enrichment showed that NTS<RT, but in the layer of2-5cm get the opposite result. The contribution rate of organic carbon in total soil organic carbon shown as:NTS>RT.The enrichment of NTS is small, but its organic carbon storage and the contribution of soil organic carbon is high,means under the condition of continuous NTSthe clay organic carbon accumulation are reaching a new equilibrium, and improving the content of soil organic matter.Tilling also affects the organic carbon content of the silt and sand. In the0-2cm, the concentration, stock and enrichment of silt organic carbon showed:NTS<RT, but in sand has the opposite result. In no tillage systerm, the index of concentration, stock and enrichment increasedwith stover mulching quantity increased. The results showed that implementation ofNTShelp increasethe organic carbon content in the larger particles.7. The effect of the NTS influence on amino sugars mainly reflected in the sand. The amount of soil amino sugars and the amino monosaccharides (GluN, GlaN and Mur) in the concentration, stock and enrichmen of sand increased with stover mulching quantity increased, and the no-tillage treatment was higher than RT. The reduction of tilling and fresh organic material created a good habitat for soil microorganisms, thus speeding up the accumulation and transformation of microorganisms of organic carbon. The effect of five consecutive years of no-till was not obvious for the amount of clay soil amino sugar. However, the amino sugar in the concentration, stockshowed increased with stover mulching quantity increased, while in the enrichment and coefficients has the opposite result.To sum up, the implementation of NTS helpful for the improvement of the soil physical and chemical properties and add the content of soil organic matter. But the accumulated temperature of soil is low in the northeast, a large number of stover mulching is bad to improve the soil temperature before sowing. It is suggested that different regions to choose the appropriate amount of stover mulching according to the actual situation. This study showed that the results of the whole mechanization of the actual effect on corn growth and yield, is not the same as the agronomic conditions. Therefore, no-tillage effects on agricultural production, with agricultural machinery and implement quality improvement, it is need to be further research. In addition, the short-term stover mulching increases the soil organic matter content. However, the increased only exist in the surface layer within2cm. In the premise of keeping the existing soil environment, how to improve the content of soil organic matter will be an important research direction of black soil in Northeast china. |
PDF Full Text Request