Subjects: Biology >> Ecology submitted time 2017-11-29 Cooperative journals: 《中国生态农业学报》
Abstract： Based on a long-term experiment on maize-soybean relay intercropping system in Huanjiang Observation and Research Station for Karst Ecosystem, Chinese Academy of Sciences, the effects of straw in place of chemical potassium on the yield of spring maize and soil potassium balance were investigated, aiming to provide scientific basis for the rational use of straw and fertilizer in karst peak-cluster depression. The experiment was started in 2006, and the data were collected during 2010-2014. Four treatments with four repetitions were discussed in this study, including CK (no fertilizer), NPK (chemical fertilizer), C7S3 (in which 30% K from the straw and 70% K from the chemical fertilizer.), C4S6 (60% K from the straw and 30% from the chemical fertilizer). The results showed that: ⑴ the annual yields of spring maize in fertilization treatments during the 5 years were 4.12 ~ 4.17 times than that in no fertilizer treatment. The corn yields in C7S3 and C4S6 were 98.3% and 98.7% of that in NPK, respectively. The yields of grain and straw increased with time on. ⑵ compared with CK, fertilization application could significantly increase the K amount in maize straw with 2.21 ~ 2.53 times than that in CK. And fertilization application could significantly increase N, P and K absorption amounts in maize grain (P < 0.01), but there was no significant difference among fertilizer treatments (P > 0.05). ⑶ there were no significant differences for recovery efficiency, absorption efficiency, agronomic efficiency and partial factor productivity for potassium during the NPK, C7S3 and C4S6 treatments. ⑷ the annual surplus amount of potassium in NPK was 3.00 kg∙hm-2, which was higher than that in C7S3 (with minus 1.90 kg∙hm-2). The most annual surplus amount of potassium appeared in C4S6, with 8.22 kg∙hm-2, and the Surplus of potassium was 7.4%. ⑸ Compared to the beginning of the experiment(2006), soil rapidly available potassium declined by 15.9% in 2014; The fertilization application significantly increased the amount of rapidly available potassium (P < 0.01). The orders of annual amount of rapidly available potassium during 2010 ~ 2014 in fertilizer treatments were that: NPK > C7S3 > C4S6, with no difference in treatments (P > 0.05).⑹ after eight years of cultivation, soil slowly available potassium declined by 10.9% in CK, slightly declined in C4S6 with no more than 5%, slightly increased in NPK by 1.3%, and increased in C7S3 by 22.4%. Overall, the application of straw returning to replace some potassium fertilizer was suitable for the soil in karst peak-cluster depression, as it could not only maintain the yield of spring maize, but also sustain potassium dynamic balance. And 60% of the straw potassium substitution could be more suitable for sustaining potassium balance, while 30% of the straw potassium substitution could be more beneficial to improve soil slowly available potassium.
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