不同部位玉米植株残体在土壤中腐解及养分释放特征

Decomposition and Nutrient Release Characteristics of Different Parts of Maize Plant Residues in Soil

为明确不同部位玉米植株残体在土壤中腐解及养分释放特征,对探究秸秆还田养分循环利用具有重要意义。试验共设置6个残体类型,分别为叶片残体(LB)、叶鞘残体(LS)、苞叶残体(PB)、茎皮残体(SB)、茎髓残体(SP)、根茬残体(R),以整株秸秆残体(WS)作为对照。采用田间试验与盆栽试验相结合的方法,田间试验主要分析玉米植株各部位残体在土壤中的降解速率、纤维组分含量及养分释放规律,盆栽试验则模拟不同部位玉米植株残体粉碎还田对土壤养分的影响。结果表明:田间腐解试验中,随着腐解时间的增加,各部位残体纤维素、半纤维素含量均呈现不同程度的降低,腐解速率表现为LB>PB>SP>LS>WS>SB>R,根茬残体纤维素、半纤维素含量最低,腐解最缓慢,3种叶残体的纤维素、半纤维素含量较低,但其腐解速率最大;腐解过程中各部位残体养分释放状况均表现为钾(K)>磷(P)>氮(N),各部位残体氮、磷、钾的累积释放率分别为25.07%~36.71%,38.35%~45.80%,70.34%~89.01%;进一步分析得到,质量损失率与纤维素、半纤维素含量呈显著负相关,与各养分释放率呈极显著正相关。在盆栽试验中,与秸秆不还田对照处理相比,不同部位玉米植株残体还田均不同程度提高了土壤碱解氮、速效磷、速效钾含量。玉米植株叶片残体具有较好的降解和较高的养分释放率,与其他部位相比能显著提升土壤中速效养分的含量。

Clarifying the decomposition and nutrient release characteristics of different parts of maize plants in soil is of great significance for exploring nutrient recycling in straw returning.The ex⁃periment set up a total of six parts of residue type:Leaf Blade(LB),Leaf Sheath(LS),Perichaetial Bract(PB),Stem Bark(SB),Stem Pith(SP),and Root(R),and whole straw residue(WS)was used as the control.The methods of field experiment and pot experiment were combined.The field experi⁃ment mainly analyzed degradation rate,fiber content and nutrient release rule of maize plant residues in soil,while the pot experiment simulated the effect of maize plant residues crushing and returning to the field on soil nutrients.The results showed that in the field decomposition test,with the increase of decomposition time,the content of cellulose and hemicellulose in all parts decreased in different degrees,and the decomposition rate was LB>PB>SP>LS>WS>SB>R.The content of cellulose and hemicellulose in the root stubble was the lowest,and the decomposition rate was the slowest.The con⁃tent of cellulose and hemicellulose in the three leaf residues was the lowest,but the decomposition rate was the highest;In the process of decomposition,the release of nutrients from residues in each part was Potassium(K)>Phosphorus(P)>Nitrogen(N),and the cumulative release rates of nitrogen,phosphorus and potassium in each part were 25.07%-36.71%,38.29%-45.55%and 70.37%-89.01%,respectively.Further analysis showed that mass loss rate was negatively correlated with the content of cellulose and hemicellulose,and positively correlated with the release rate of nutrients.In the pot ex⁃periment,compared with the control treatment of not returning straw to the field,the return of maize plant residues from different parts of the field increased soil alkali-hydrolyzed nitrogen,available phosphorus and available potassium contents.Leaf blade residues had better degradation and higher nutrient release rate,which could significantly increase the content of available nutrients in soil com⁃pared with other parts.