秸秆颗粒化还田加速腐解速率提高培肥效果

为了探索将玉米秸秆压缩成颗粒后还田培肥土壤的可行性,研创新型秸秆还田方式,采用尼龙网袋埋藏法,研究秸秆颗粒化还田与常规粉碎秸秆还田(对照)在盆栽培养条件下的腐解与养分释放特征,以及对土壤呼吸的影响。结果表明,相同质量的秸秆颗粒化后其堆积密度为对照的4.8倍,可显著改善其还田性,提高土壤消纳秸秆的能力。秸秆颗粒化后还田可显著提升秸秆的腐解速率,培养期内前60 d,秸秆颗粒平均腐解速率比对照提升31.68%;培养300 d后,其累积腐解率达80.81%,比对照高出8.7个百分点;估算可比对照提前30 d腐解超过50%,提前14 d完全腐解。秸秆颗粒化还田可显著提升秸秆养分释放速率,培养期前60 d尤为明显;培养300 d后,秸秆颗粒的碳(C,carbon)和氮(N,nitrogen)累积释放率比对照分别提高了11.0和13.2个百分点,但磷素(P,phosphorus)和钾(K,kalium)累积释放率与对照无显著差异(P0.05);估算C、N、P、K养分分别释放超过50%的时间比对照提前15~125 d,提前9 d释放全部养分。此外,秸秆颗粒化还田在培养期前260 d可显著提高土壤呼吸速率,培养期间平均土壤呼吸速率比对照提高18.03%。因此,秸秆颗粒化还田可实现高效快速的培肥土壤,在农业生产中具有较高的推广应用价值。

Returning granulated straw for accelerating decomposition rate and improving soil fertility

Abstract: Returning crop straw into the soils is one of the important steps towards sustaining and improving soil fertility. As a large agricultural country, China has more than 700 million tons crop straw engendered annually. Various practices of returning straw, such as chopping, mulching and deep burying, have been invented and used widely in rural areas. However, low yield of crop always occurs in the next season if excessive amount of straw has been returned, which even leads to plant disease and insect pest. Further, environmental issues increase due to a lot of crop straw returning to the field. Thus, effective techniques for returning crop straw and increasing soil productivity should be developed to cope with these challenges. As an innovative way of returning straw, we granulated the maize straw with the help of a straw granulated machine and then returned them into the soils. To evaluate the effects of granulated straw and chopped straw (standing for the control) on straw decomposition, nutrient release and soil respiration, a successive laboratory incubation experiment was conducted at Chinese Academy of Agricultural Sciences in Beijing, China. After granulating, the bulk density of maize straw was 254.09 kg/m3, 4.8 times the value of the control. As a result, the rates of straw returning increased considerably in a unit soil. In this experiment, both the granulated and chopped straw were put in several nylon bags and then buried into soils at a depth of 15 cm. In the course of the experiments, they were sampled randomly and determined. In the earlier 60 d, the mean decomposition rate of granulated straw was 31.68% higher than that of the control. After 300 d, the cumulative decomposition rate of granulated straw was 80.81%, 8.7percentage points higher than that of the control. Based on the regression analysis between nutrient releasing rate and decomposition time for different pre-treatments of maize straw, the granulated straw treatment was 30 or 14 d earlier than the chopped straw treatment when they half or completely decayed, respectively. In addition, the granulated straw treatment significantly increased the nutrient release rate throughout the entire incubation period, especially in the early 60 d. After 300 d, the granulated straw treatment increased the cumulative release amount of C (carbon) and N (nitrogen) by 11.0 percentage points and 13.2 percentage points compared to the corresponding level of the control, respectively. However, no significant differences were found for the cumulative release amount of P (phosphorus) and K (potassium) between the granulated and chopped straw treatment. According to the results of data fitting, the time of more than 50% releasing nutrient for the granulated straw treatment was 15-125 d earlier than the control; in contrast, it was 9 d earlier than the control when its nutrient was released completely. In addition, the mean value of soil respiration rate for the granulated straw treatment was 18.03% greater than the control in the earlier 260 d. In conclusion, maize straw that was granulated before returning into soils can fast and effectively improve soil fertility; and thus, it is worthy widely applying in agricultural production.