春玉米田翻压绿肥腐解及养分释放特征研究

采用尼龙网袋埋田法,研究越冬绿肥二月兰在春玉米田土壤腐解特征及养分释放规律,为华北地区春玉米减肥增效技术研究提供理论依据。结果表明,二月兰还田0~10d腐解速率最高,达1.21g/d,阶段内累积腐解率为28.94%;11~45d进入缓慢腐解期,腐解速率为0.44g/d,阶段累积腐解率占比37.45%;46~123d腐解速率稳定在0.03g/d,至玉米收获时累积腐解率达71.26%。二月兰腐解期内养分累积释放率表现为钾>碳>磷>氮,分别达94.90%、76.46%、56.35%和53.83%,且钾、碳和氮均在还田0~45d累积释放量最高,而磷在还田0~3d出现“增高富集”后快速释放。据测算,二月兰腐解期内氮、磷、钾释放量分别为26.82、4.04和35.88kg/hm²。因此,华北地区绿肥二月兰还田可适当替代化学肥料,依据养分释放规律,春玉米前期应重氮磷、轻钾,后期补氮钾。

Study on Decomposition and Nutrient Release Rule of Green Manure Returned in Spring Maize Field

The nylon mesh bag burying method was used to study the decomposition and nutrient release rule of Orychophragmus violaceus as green manure returned in spring maize field to provide theoretical basic for reducing chemical fertilizer input and increasing nitrogen use efficiency of spring maize in North China Plain. The results showed that the maximum decomposition speed rate of O.violaceus was in 0-10d during the experiment duration, average decomposition speed rate and accumulation decomposition ratio were reached 1.21g/d and 28.94%, respectively. The O.violaceus decomposed slowly during 11-45d, which the average decomposition speed rate was 0.44g/d, and the accumulation decomposition ratio was accounted as 37.45%. After that, the decomposition was the slowest by the average decomposition speed rate was only 0.03g/d during 46-123d, and the cumulative decomposing rate reached 71.26% when maize was harvested. The accumulation nutrient ratio was K > C > P > N, and the accumulation release ratios were 94.90%, 76.46%, 56.35%, and 53.83%, respectively, during the decomposing period. The internal cumulative release of K, C, and N was the highest in 45 days of incubation, while P content was increased in three days and then decreased fast. By estimation, N, P, and K released from O.violaceus were amount to 26.82, 4.04, and 35.88kg/ha. Therefore, O.violaceus as green manure returned in the field could appropriatly replace chemical fertilizer in North China Plain, which should apply more N and P, and less K in the early stage of spring maize, and supplied some N and K in the late stage because of the nutrient release rule of O.violaceus.