稻麦秸秆不同部位在淹水土壤中腐解进程的差异

发布时间：2018-06-04 12:27

本文选题：茎秆 + 叶鞘　；参考：《扬州大学》2015年硕士论文

【摘要】：随着我国粮食产量不断提高,各种作物秸秆产量相应增加,目前秸秆年产量己突破7亿t,其中稻麦秸秆增加量尤其突出。加之全社会环保意识的不断加强,秸秆露天焚烧现象目前已得到有效的控制,秸秆直接还田正日益普及。大量秸秆直接还田,势必影响农田土壤理化及生物学过程,进而影响下茬作物幼苗的生长。因此,探究秸秆在土壤中的腐解过程对于阐明秸秆还田对土壤肥力与作物生长的影响机制以及秸秆还田配套措施的制订具有重要意义。水稻与小麦等禾谷类作物的秸秆通常有叶鞘包裹,茎秆与叶鞘在组成与性质上存在较大差异,而目前关于水稻和小麦秸秆的茎秆与叶鞘在土壤中腐解进程差异的研究报道尚不多见。本研究以水稻和小麦秸秆为材料,将秸秆分为茎秆及叶鞘两部分,通过测定淹水培养过程中茎秆和叶鞘的质量亏损和秸秆材料中可溶性糖、半纤维素、纤维素、木质素的含量变化以及土壤溶液中的溶解性有机碳(DOC)含量、NH4’浓度、pH的动态,分析水稻、小麦秸秆的茎秆和叶鞘在腐解进程上的差异及其与施氮的关系。主要研究结果如下：(1)水稻、小麦秸秆中茎秆和叶鞘占秸秆总重的比例存在差异,水稻秸秆中茎秆和叶鞘分别占秸秆总重的37%和63%,而小麦秸秆中两者分别占56%和44%。水稻秸秆茎秆的C/N显著低于叶鞘,而小麦秸秆正相反。无论是水稻秸秆还是小麦秸秆,茎秆的纤维素含量显著高于叶鞘,而半纤维素及木质素含量显著低于叶鞘,茎秆与叶鞘在可溶性糖含量上无明显差异。(2)稻麦秸秆中茎秆和叶鞘的腐解均表现为前期快后期慢的特点,其中小麦叶鞘前期腐解速率最大,小麦茎秆最慢。随着腐解进程的推进,四者的腐解速率不断下降,且小麦叶鞘腐解速率下降幅度最大。至培养结束(60d),累积腐解率为小麦叶鞘水稻叶鞘水稻茎秆小麦茎秆。在完成相同的腐解进度时,小麦叶鞘所需时间最短,而小麦茎秆所需时间最长。说明小麦秸秆在淹水腐解的初期由于叶鞘的快速腐解表现出整体腐解速度较较高,但因其茎秆腐解较缓慢,很快进入腐解缓慢期；故小麦秸杆快速腐解时期集中在初期,总体腐解困难,腐解周期长。而水稻秸秆的茎秆和叶鞘腐解速率相当,具有一个较长时间的快速腐解阶段。实验中施氮对于水稻茎秆和叶鞘的腐解有飞定的抑制作用,表现在降低了水稻茎秆和叶鞘的累积腐解率；对于小麦茎秆和叶鞘的腐解则有一定的促进作用,表现在施氮提高了小麦茎秆和叶鞘的累积腐解率；此外,施氮均提高了稻麦茎秆和叶鞘的初始腐解速率。(3)经60d腐解,水稻秸秆茎秆和叶鞘可溶性糖的累积腐解率分别为80.3%和76.1%,而小麦秸秆分别为64.2%和72.4%；四种秸秆材料中,小麦秸秆叶鞘中可溶性糖腐解速率最快,而小麦茎秆可溶性糖腐解最慢。与水稻秸秆相比,小麦茎秆中半纤维素与木质素较难腐解,60d累积腐解率仅分别为38.5%和28.4%；而小麦叶鞘中半纤维素与木质素的起始腐解速度较快,但随腐解时间的延长下降幅度较大。秸秆材料中纤维素腐解特征与半纤维素和木质素明显不同,水稻叶鞘纤维素的起始腐解速率最快,但下降幅度也最大；小麦茎秆纤维素起始腐解速率最慢,但衰减幅度很小。从完成相同腐解进度所需的时间来看,水稻秸秆纤维素腐解主要在前期进行,而小麦纤维素的腐解持续时间较长。施氮抑制了水稻茎秆和叶鞘的半纤维素,水稻茎秆、小麦茎秆和小麦叶鞘中纤维素以及水稻茎秆、水稻叶鞘和小麦茎秆木质素的腐解,而对于小麦茎秆和叶鞘半纤维素、水稻叶鞘的纤维素及小麦叶鞘的木质素腐解有一定的促进作用。(4)供试秸秆材料的腐解提高了土壤中DOC的水平,所有处理中DOC浓度呈先上升后下降的趋势,水稻茎秆处理的DOC峰值最高,小麦茎秆的DOC峰值最低。土壤溶液pH在6.4-8.4之间波动,到培养期结束时,不同秸秆处理土壤溶液pH的高低次序为：水稻茎秆与水稻叶鞘小麦茎秆与小麦叶鞘。水稻茎秆和小麦叶鞘处理前15d土壤溶液NH4+浓度较高,随后趋于平稳,而小麦茎秆处理土壤溶液中NH4’浓度缓慢上升,但其浓度远低于其他三种秸秆材料处理。施氮降低了水稻茎秆和小麦叶鞘处理的腐解前期DOC峰值,但提高了土壤溶液中NH4+的浓度。
[Abstract]:With the continuous improvement of grain production in China, the yield of various crop straws has been increased correspondingly. The annual yield of straw has exceeded 700 million T, especially the increase of rice and wheat straw is especially prominent. In addition, the consciousness of environmental protection in the whole society has been strengthened. The phenomenon of straw burning has been effectively controlled and the straw returning to the field is becoming more and more popular. After returning to the field, it is bound to affect the physical and biological processes of farmland soil and biological processes, and then affect the growth of the seedlings of the next crop. Therefore, it is of great significance to explore the decomposition process of straw in soil for clarifying the effect mechanism of straw returning to soil fertility and crop growth and the formulation of straw returning supporting measures. The crop straw is usually covered with leaf sheath, and there is a great difference in the composition and nature of the stem and leaf sheath. At present, there are few reports on the difference between the stalk and the leaf sheath of the rice and wheat straw in the soil. In this study, rice and wheat straw were used as materials to divide the straw into two parts of stem and leaf sheath. The mass loss of stem and leaf sheath during the submerged culture and the changes in the content of soluble sugar, hemicellulose, cellulose and lignin in straw materials and the content of dissolved organic carbon (DOC) in soil solution, NH4 'concentration, and the dynamics of pH, analysis of the difference between the stalk and the leaf sheath of rice, wheat straw and leaf sheath in the process of decomposition and its application to nitrogen application. The main results are as follows: (1) the proportion of straw and leaf sheath in rice straw accounts for the total weight of straw. The stem and leaf sheath of rice straw accounted for 37% and 63% of total straw weight respectively, while 56% of the wheat straw and 44%. rice straw stalk were significantly lower than that of the leaf sheath, but the wheat straw was opposite. Straw or wheat straw, cellulose content of stem was significantly higher than leaf sheath, but hemicellulose and lignin content was significantly lower than the leaf sheath, and there was no significant difference in soluble sugar content between stem and leaf sheath. (2) the decomposition of stem and leaf sheath in rice and wheat straw were characterized by the slow early stage in the early stage, and the maximum decaying rate of wheat leaf sheath in the early stage was the largest. The stalk of wheat was the slowest. With the advancement of the decay process, the decay rate of the four was decreasing, and the Ye Qiaofu solution rate decreased greatly. To the end of culture (60d), the cumulative decay rate was the stalk of rice stem of rice leaf sheath of wheat leaf sheath. It takes time for the longest time. It shows that the rapid decomposition rate of the leaf sheath in the early period of the leaf sheath of wheat straw shows a higher overall decay rate, but it quickly enters the slow decay period because of the slow decay of its stem. Therefore, the rapid decomposition period of wheat straw is concentrated in the early stage, and the overall decomposition is difficult and the decay period is long. The rate of scabbard decomposition was similar, with a long period of rapid decomposition. The inhibition effect of Nitrogen Application on the decomposition of rice stem and leaf sheath in the experiment was shown to decrease the cumulative decay rate of rice stem and leaf sheath, and to promote the decomposition of wheat stem and leaf sheath. In addition, nitrogen application increased the initial decomposition rate of the stem and leaf sheath of rice and wheat. (3) the cumulative decomposition rate of soluble sugar in rice straw stalk and leaf sheath was 80.3% and 76.1% by 60d decomposition, while wheat straw was 64.2% and 72.4%, respectively. In the four straw material, the soluble sugar rot in the leaf sheath of wheat straw was soluble. The solution rate was the fastest, but the soluble sugar decomposition of wheat stalk was the slowest. Compared with the rice straw, the hemicellulose and lignin in the wheat stalk were more difficult to decompose, and the cumulative decomposition rate of 60d was only 38.5% and 28.4%, while the initial decomposition rate of hemicellulose and lignin in the leaf sheath of wheat was faster, but it decreased with the prolongation of the decomposition time. The decomposition of cellulose in the material is different from the hemicellulose and lignin, and the initial decay rate of the cellulose in the leaf sheath of rice is the fastest, but the decrease is the most, but the decay rate is the slowest, but the attenuation is very small. The decomposition of cellulose in wheat lasted for a long time. Nitrogen application inhibited the hemicellulose of rice stem and leaf sheath, cellulose and rice stem, leaf sheath and wheat stalk lignin in rice stem, wheat stem and wheat leaf sheath, and cellulose of wheat stem and leaf sheath hemicellulose, and the cellulose of rice leaf sheath. The lignin decomposition of the leaf sheath of wheat had a certain promotion effect. (4) the decomposition of the straw material increased the level of DOC in the soil, and the concentration of DOC increased first and then decreased in all treatments, the peak of DOC in the rice stem treatment was the highest, and the peak of DOC in the wheat stem was the lowest. The soil solution pH was fluctuated between 6.4-8.4 and at the end of the culture period. The order of soil solution pH in different straw treatments is: rice stem and rice leaf sheath wheat stem and wheat leaf sheath. The concentration of NH4+ in 15d soil solution before the treatment of rice stem and wheat leaf sheath is higher, then tends to be stable, but the concentration of NH4 'in the soil solution of Wheat stem is slowly rising, but its concentration is far lower than the other three kinds of straw wood. Nitrogen treatment reduced the peak DOC value of rice stem and wheat leaf sheath during the early stage of decomposition, but increased the concentration of NH4+ in soil solution.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S141.4

【相似文献】