秸秆颗粒化高量还田快速提高土壤有机碳含量及小麦玉米产量

针对黄淮海地区秸秆还田难度大不利于土壤快速培肥的问题,探讨秸秆颗粒化高量还田快速提高土壤有机碳的可行性。采用2a的田间定位试验,设置秸秆不还田(CK)、秸秆颗粒12 000 kg/hm~2(KL1)、秸秆颗粒36 000 kg/hm~2(KL3)、粉碎秸秆12 000 kg/hm~2(FS1)、粉碎秸秆36 000 kg/hm~2(FS3)5种用量30～40 cm还田处理,研究了颗粒化秸秆高、低量还田对土壤有机碳、养分元素比例平衡以及小麦-玉米产量的影响。结果表明,秸秆还田2a内对20～40、40～60 cm土层有机碳含量影响显著,其中FS1提升幅度最低,分别为7.2%(20～40cm)、5.9%(40～60cm),KL3提升幅度最高,分别为12.3%(20～40 cm)、11.1%(40～60 cm)。与粉碎还田相比,秸秆颗粒化还田能在还田1a显著提高土壤有机碳含量,KL3较FS320～40、40～60 cm土壤有机碳分别提高1.7%、1.3%,KL1较FS120～40、40～60 cm分别提高0.8%、0.7%。另外,高量还田具有大幅提高有机碳的优势,FS3较FS1分别提高20～40 cm土壤有机碳1.7%～3.9%、40～60 cm土层有机碳0.7%～3.8%,KL3较KL1分别提高20～40 cm有机碳2.4%～4.7%、40～60 cm土层1.3%～5.1%。秸秆颗粒高量还田(KL3)在各生长季均具有较高的有机碳累积速率,且总体均值最高。秸秆颗粒化高量还田能在一定程度上提高土壤碳氮比(RCN)、碳磷比(RCP)、碳钾比(RCK),促使土壤养分比向高肥力方向转化。该试验中秸秆颗粒化高量还田连续4个生长季增产4.57%、11.40%、10.87%、8.87%,增产效果显著。综上可见,秸秆颗粒36000kg/hm~2深埋还田最有利于黄淮海地区土壤有机碳的提高,在解决土壤"碳饥饿"等问题、保障农业可持续发展上具有重要意义。

High dosage of pelletized straw returning rapidly improving soil organic carbon content and wheat-maize yield

Abstract: There is a large straw production in the wheat-maize rotation system of Huang-Huai-Hai Plain in China, which increases the difficulty of straw utilization so that soil fertility cannot be effectively supplemented and the environmental pollution caused by straw burning is aggravated. In view of the difficulty of the large straw returning which is not conducive to rapidly improve soil fertility, the pelletized straw returning was created, which made the same area of farmland hold more straw. But it is unclear that if increasing the amount of pelletized straw has a positive effect on soil organic carbon (SOC) content. Therefore, the aim of this article was to explore the effects of the high and low straw return dosages on SOC content, SOC accumulation rate and soil nutrient elements ratio in 0-20, >20-40 and >40-60 cm soil layer and the yield of wheat-maize during the two-year trial period. Five kinds of straw managements were treated by 2-year field location test, including non-straw returning (CK), 12 000 kg/hm2 pelletized straw returning (KL1), 36 000 kg/hm2 pelletized straw returning (KL3), 12 000 kg/hm2 chopped straw returning (FS1), and 36 000 kg/hm2 chopped straw returning (FS3). Each straw treatment was a mixture of half wheat straw and half corn straw. The results showed that the SOCs in >20-40 and >40-60 cm soil layers were significantly affected by the 2-year straw returning. Among the four straw returning treatments, FS1 had the lowest increase, which was only 7.2% in >20-40 cm soil layer and 5.9% in >40-60 cm soil layer higher than that of CK, however, KL3 had the highest increase, which was 12.3% in >20-40 cm soil layer and 11.1% in >40-60 cm soil layer higher than that of CK. Compared with the chopped straw returning treatment, the pelletized straw returning treatment rapidly increased SOC content, which manifested that SOC content of KL3 was 1.7% in >20-40 cm soil layer and 1.3% in >40-60 cm soil layer higher than that of FS3 after 1-year straw returning, and SOC content of KL1 was 0.8% in >20-40 cm soil layer and 0.7% in >40-60 cm soil layer higher than that of FS1 after 1-year straw returning. In addition, high dosage straw returning had the advantage of improving SOC content greatly. Compared with the low dosage straw returning, FS3 increased SOC content by 1.7%-3.9% in >20-40 cm soil layer and 0.7%-3.8% in >40-60 cm soil layer, and KL3 increased SOC content by 2.4%-4.7% in >20-40 cm soil layer and 1.3%-5.1% in >40-60 cm soil layer. KL3 also had the higher SOC accumulation rate in each growing season, and the overall mean value was the highest among the five treatments. What''s more, KL3 improved soil carbon-nitrogen ratio (RCN), carbon-phosphorus ratio (RCP) and carbon-potassium ratio (RCK) to a certain extent, which indicated that high dosage pelletized straw returning promoted soil nutrient conversion to a higher fertility direction. In this experiment, KL3 significantly increased the wheat yield by 4.57% and 10.87%, the maize yield by 11.40% and 8.87%, respectively in the 2-year trial period. In a conclusion, 36 000 kg/hm2 pelletized straw deep returning is the most beneficial to promote the SOC in the Huang- Huai-Hai Plain, which has a great significance in solving the problem of soil "carbon starvation" and ensuring the sustainable development of agriculture.