麦——稻秸秆机械粉碎全量还田技术模式探讨

为直接有效处理并利用秸秆,笔者提出麦—稻秸秆机械粉碎全量还田技术模式,概述了该模式的意义及流程,分析了该模式的增产增效情况,总结了技术要点,提出了该模式的适宜区域与注意事项,以期为秸秆综合利用提供借鉴。

Status Quo of Collection and Utilization of Rice and Wheat Straw in Jiangsu Province and the Countermeasures

A case study of Jiangsu Province was conducted using questionnaires and field survey to explore the status quo of the collection and utilization of rice and wheat straw of the province. Problems in collecting the straw were analyzed taking into account meteorological data of the rice and wheat harvesting seasons in the region. Results show：（1） Currently, the main handling way of rice and wheat straw was directly returning to field. The peasant households of straw returning from investigated townships A and B respectively occupied 22.01% and 28.75% of investigation households, and both of the two townships had a considerable portion of the straw wasted or improperly disposed. In township B, over 50% of the farmer households surveyed failed to make sure of any of the straw, and as high as over55% of the straw was discarded or burnt.（2） During the rice and wheat harvesting seasons, the ten-day precipitation was among 7.21-87.28 mm, and the ten-day precipitation days were among 1.53-5.00 d. Such weather not only affected timely harvesting of rice and wheat, but also seriously impeded baling, transportation and storage of straw.（3） As the crops must be harvested in a relatively short and concentrated time period, large volumes of straw were turned out within a few days.Moreover, harvesting of the first crop often coincided with sowing, leaving little time available for straw collection.（4） Straw collection was very low in economic benefit.A farmer can only get 60-90 RMB per day from straw collection and transportation,which was much lower than what they can get by working as migrant workers in the city.（5） Machines designed for straw collection were rare and those now used in the operation were low in efficiency and needed to be improved technically,which directly affected the efficiency of straw collection. The above-listed findings indicates that time shortage, negative weather condition, low benefit and low mechanization level were major factors affecting straw collection. To solve the problems,the following proposals were brought forth, that is, improving the economic benefit of straw collection as a driving force, accelerating the research and development of rice and wheat sheaf-binding reaping machine, and setting up a long-term operational mechanism for straw recovery, in the hope that this study may provide some useful ideas to help solve the problems.

Study on Environmental and Economic Benefits of Rice and Wheat Rotation with Swine Manure-Straw Returning

[Objective] The aim was to investigate the application effect of swine manure-straw returning and to determine the best mode. [Method] A field experiment under rice and wheat rotation with different swine manure-straw treatments was con- ducted to study the growth characters and output of rice and wheat, calculate the economic benefit and carbon dioxide emission reduction, and analyze the best mode of swine manure applying-straw returning. [Result] The swine manure-straw returning was conducive to the growth of crop, the highest outputs of rice and wheat were on the treatment of ＂30% swine manure and 20% straw and 50% chemical fertiliz- er＂, they were 7 874.57 and 6 427.00 kg/hm^2, and saved cost about 5 146.35 Yuan/hm^2, increased input 5 312.56 and 3 931.93 Yuan/hm^2, the greenhouse gas e- mission reduction was 1.30 t/hm^2 （calculated according to carbon dioxide on a dry basis）. [Conclusion] The treatment of ＂30% swine manure and 20% straw and 50% chemical fertilizer＂ was the best mode of swine manure-straw returning.

Environmental Effects of Returning Rice and Wheat Straw to Fields

Based on advances in returning rice and wheat straw to fields at home and abroad, environmental physical, chemical and ecological effects of returning rice and wheat straw to fields were analyzed. The results show that returning straw to fields can enhance soil porosity, reduce soil bulk density, and increase the ca- pacity of soil to preserve water, fertilizer and temperature. Besides, it can improve the content of organic matter, nitrogen, phosphorus and potassium in soil, of which the increase of potassium content is the most obvious. Meanwhile, it can provide energy and nutrients for microorganisms in soil and change the activity of soil enzymes, of which it affects invertase most greatly and enhances the activity of ure- ase but has no effect on neutral phosphatase. In addition, it can enhance the total quantity of microorganisms in soil obviously, and the increase correlates positively with the quantity of straw returning to fields. Finally, returning straw to fields can promote the sustainable development of agriculture.

Effect of Incorporation of Wheat Straw and Urea into Soil on Biomass Nitrogen and Nitrogen-Supplying Characteristics of Paddy Soil

Pot experiments were carried out to study the effect of incorporation of wheat straw and/ or urea into soil on biomass nitrogen and mineral nitrogen and its relation to the growth and yield of rice. The combined application of wheat straw and urea increased much more biomass nitrogen in soil than the application of wheat straw or urea alone and consequently increased the immobilization of urea nitrogen added and reduced the loss of urea nitrogen. An adequate nitrogen-supplying process to rice plant could be obtained if C / N ratio of the material added was about 20. The three yield components of rice were affected significantly by the status of nitrogen supplying. More than 30mg N / kg soil of mineral nitrogen at effective tillering stage, panicle initiation stage and filling stage should be maintained in order to get high rice yield, though the criteria varied with the different experimental conditions.

Decomposition and Products of Wheat and Rice Straw from a FACE Experiment Under Flooded Conditions

Winter wheat and rice straw produced under ambient and elevated CO2 in a China rice-wheat rotation free-air CO2 enrichment （FACE） experiment was mixed with a paddy soil at a rate of 10 g kg^-1 （air-dried）, and the mixture was incubated under flooded conditions at 25℃ to examine the differences in decomposition as well as the products of crop residues produced under elevated CO2. Results showed that the C/N ratio and the amount of soluble fraction in the amended rice straw grown under elevated CO2 （FR） were 9.8% and 73.1% greater, and the cellulose and lignin were 16.0% and 9.9% lesser than those of the amended rice straw grown under ambient CO2 （AR）, respectively. Compared with those of the AR treatment, the CO2-C and CH4-C emissions in the FR treatment for 25 d were increased by 7.9% and 25.0%, respectively; a higher ratio of CH4 to CO2 emissions induced by straw in the FR treatment was also observed. In contrast, in the treatments with winter wheat straw, the CO2-C and CH4-C emissions, the ratio of straw-induced CH4 to CO2 emissions, and the straw composition were not significantly affected by elevated CO2, except for an 8.0% decrease in total N and a 9.7% increase in C/N ratio in the wheat straw grown under elevated CO2. Correlation analysis showed that the net CO2-C and CH4-C emission from straw and the ratio of straw-induced CH4 to CO2 emissions were all exponentially related to the amount of soluble fraction in the amended straw （P 〈0.05）. These indicated that under flooded conditions, the turnover and CH4 emission from crop straw incorporated into soil were dependent on the effect of elevated CO2 on straw composition, and varied with crop species. Incorporation of rice straw grown under elevated CO2 would stimulate CH4 emission from flooded rice fields, whereas winter wheat straw grown under elevated CO2 had no effect on CH4 emission.