冻融条件下不同秸秆还田方式对土壤有效磷影响研究

发布时间：2018-04-06 23:38

本文选题：冻融作用　切入点：有效磷　出处：《沈阳农业大学》2017年硕士论文

【摘要】：作物秸秆还田后可通过改变土壤理化性质和环境来影响作物生长期土壤磷素有效性。在我国东北地区,由于春季反复冻融作用土壤结构发生改变,进而导致土壤有效磷含量极不稳定。目前关于不同秸秆还田方式对冻融期土壤磷有效性影响作用及机理的报道并不多见。本试验采用室内模拟方法,研究冻融作用下传统秸秆还田和秸秆热解成生物炭还田对冻融对棕壤有效磷以及相关性质变化规律,探讨不同秸秆还田方式对东北春季作物生长初期土壤养分供应状况影响机理,研究结果在东北地区秸秆还田实践和理论方面均有一定的指导意义。得出主要结论如下:(1)段状和粉状还田均可以显著提高土壤中有效磷的含量,但在同一施加量下粉状秸秆提高的明显。试验中各处理前5次冻融循环其土壤中有效磷含量不稳定,随着冻融试验的进行其含量逐渐趋于平稳,最后还有少量上升的趋势。两种还田方式均在第5次左右土壤中的有效磷含量达到峰值,此时施加段状秸秆和粉状秸秆土壤中有效磷含量均值分别为22.23mg.kg-1、22.97mg.kg-1,较未进行冻融时分别提高了 19.58%、23.56%。(2)秸秆直接还田后,磷酸酶活性为CK施加段状秸秆施加粉状秸秆。同一种还田方式下,土壤中磷酸酶活性均为CK2%4%6%。在整个冻融循环过程中,两种秸秆还田方式下电导率大小与磷酸酶活性变化有着相似的规律。且这两种还田方式下,有效磷含量与磷酸酶活性和电导率这两个指标之间的相关性均达到显著水平。从整体来看,冻融过程中电导率对磷素的影响程度均大于磷酸酶的影响。(3)秸秆热解制成生物炭还田并培养结束后,施加生物炭量2%、4°%、6%处理有效磷含量随生物炭施入量增大而依次增加,且均明显高于对照处理20%以上。各处理在第5次冻融左右达到峰值,有效磷含量增加幅度随生物炭施加量增加而减小。在第20次冻融循环后各处理有效磷含量相对达到谷值,施加生物炭量2%、4%、6%处理有效磷含量较未冻融时分别降低了 18.9%、8.2%、9.5%。(4)分析生物炭输入后棕壤pH值、电导率、有机质和磷酸酶活性等生物化学性质对冻融作用的响应,结果为:生物炭施加除对5-30次冻融循环阶段土壤有机质含量无显著影响外,对各冻融阶段其他指标都有显著性影响。冻融作用对土壤酸碱度、有机质含量影响较显著,但是对电导率、磷酸酶活性影响不显著。在冻融循环各阶段,有机质含量、电导率与有效磷含量都呈显著正相关。(5)秸秆还田后土壤中有效磷含量均高于未还田,且同一施加量下土壤中有效磷含量总体表现为SSPSBS,无论哪种还田方式其土壤中有效磷含量均是:施加量6%4%2%CK,且呈先缓慢增加直至3-5次时迅速增加至峰值之后缓慢减少最后逐渐趋于平稳的变化趋势。
[Abstract]:Soil phosphorus availability can be affected by changing soil physical and chemical properties and environment after crop straw is returned to the field.In Northeast China, the soil structure was changed because of repeated freezing and thawing in spring, which led to the instability of soil available phosphorus content.At present, there are few reports about the effect and mechanism of different straw returning methods on soil phosphorus availability during freezing and thawing period.In this experiment, indoor simulation method was used to study the changes of available phosphorus and related properties of brown soil by traditional straw return and straw pyrolysis to brown soil under freezing and thawing.The effects of different straw returning methods on the soil nutrient supply in the early spring crop growth in Northeast China were discussed. The results of the study are of certain guiding significance in the practice and theory of straw returning to the field in Northeast China.The main conclusions were as follows: (1) the content of available phosphorus in the soil could be increased significantly by the addition of the two fractions, but under the same applied amount, the content of the available phosphorus in the soil could be increased obviously.During the first five freeze-thaw cycles, the content of available phosphorus in the soil was unstable, and gradually stabilized with the freezing and thawing test. Finally, there was a small increase in the content of phosphorus in the soil.The available phosphorus content in the soil reached its peak value at the fifth time, and the mean value of available phosphorus content in the soil was 22.23 mg 路kg ~ (-1) 路kg ~ (-1) and 22.97 mg 路kg ~ (-1), respectively, which increased 19.58% ~ 23.56.2mg 路kg ~ (-1) straw directly after returning to the field.The activity of phosphatase was that CK applied segmental straw to powdery straw.In the same way, the activity of phosphatase in the soil was CK245.During the whole freeze-thaw cycle, the electrical conductivity and phosphatase activity of the two kinds of straw returning to the field had similar regularity.The correlation between the available phosphorus content and the activity of phosphatase and the conductivity of phosphatase reached a significant level under these two ways of returning to the field.As a whole, the effect of electrical conductivity on phosphorus during freezing and thawing was greater than that of phosphatase.The content of available phosphorus increased with the increase of the amount of biochar application, and was significantly higher than that of the control treatment (above 20%).The peak value of each treatment was reached at the fifth freeze-thaw stage, and the increase of available phosphorus content decreased with the increase of the amount of biochar.After the 20th freeze-thaw cycle, the available phosphorus content of each treatment reached the valley value, and the available phosphorus content of the treatment with 2% biochar was decreased by 18.9% and 8.2%, respectively, compared with that without freezing and thawing. The pH value and electrical conductivity of brown soil were analyzed after the input of biochar.The response of biochemical properties such as organic matter and phosphatase activity to freezing and thawing was found. The results were as follows: except for no significant effect on soil organic matter content in 5-30 freezing and thawing cycles, the application of biochar had a significant effect on other indexes in each freezing and thawing stage.Freezing and thawing had significant effects on soil pH and organic matter content, but had no significant effect on electrical conductivity and phosphatase activity.In each stage of freeze-thaw cycle, organic matter content, electrical conductivity and available phosphorus content were significantly positively correlated.The content of available phosphorus in the soil under the same amount of application was SSPSBS.The available phosphorus content in the soil was 642 CKs by applying 642 CKs, and increased slowly until the peak value increased to the peak at 3-5 times and then decreased slowly.Finally, a steady trend of change.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S141.4

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