• ISSN 1008-505X
  • CN 11-3996/S
XIE Shuai, LIANG Xin-yu, SONG Ming-dan, HAN Mei, LI Zheng-peng. Characteristics of mixed decay of wheat straw-hairy vetch on the Qinghai plateau[J]. Journal of Plant Nutrition and Fertilizers, 2022, 28(4): 754-762. DOI: 10.11674/zwyf.2021613
Citation: XIE Shuai, LIANG Xin-yu, SONG Ming-dan, HAN Mei, LI Zheng-peng. Characteristics of mixed decay of wheat straw-hairy vetch on the Qinghai plateau[J]. Journal of Plant Nutrition and Fertilizers, 2022, 28(4): 754-762. DOI: 10.11674/zwyf.2021613

Characteristics of mixed decay of wheat straw-hairy vetch on the Qinghai plateau

  • Objectives Study the decomposition and nutrient release patterns of wheat straw and hairy vetch (Vicia sativa) seperately and both of them in farmland will provide theoretical and technical guidance for the management of organic materials returning to the field in Qinghai plateau.
    Methods The tested wheat straw and hairy vetch were naturally dried and cut into 2 cm long, single wheat straw (S), single hairy vetch (G), and wheat straw and hairy vetch together (G+S) were loaded into nylon mesh bags, and buried into 20 cm deep in soil for decomposition. At the 7, 14, 28, 42, 72, 117, and 162 days of burying, sample bags were dig out for measurement of required indexes.
    Results The dry matter decay rate and nutrient release rate in all the three treatments were fast in early stage and slow in later stage, and the cumulative decomposition rates were 81.93% for G treatment, 51.65% for S treatment, and 64.17% for G+S treatment. The cumulative nutrient release rate in G, S, and G+S treatments were 85.30%, 46.66% and 62.77% for C; 88.29%, 31.83% and 66.78% for N; 71.30%, 62.66% and 68.24% for P; 98.24%, 94.62% and 97.40% for K. The rapid decay period was less than 42 days, and the rapid release period for each nutrient varied from 0–7 days for C, 0–28 days for N, 0–14 days for P, and 0–42 days for K. Simulation by the bi-pool exponential decay model revealed that the proportions of easily decomposed fraction in total weight in G, S and G+S treatments were about 79.25%,53.62%, and 64.16%, respectively. The proportions of easily decomposed C, N, P were all the highest in hairy vetch treatment, and K is the highest in wheat straw treatment. The G+S treatment increased the proportion of dry matter mass, C, N, P, and K in the easily decomposable fraction compared to the predicted values in all cases, increasing dry matter mass by 1.47%, C by 6.02%, N by 22.77%, P by 5.41%, and K by 0.20%, increasing the average turnover days of C and N, and decreasing the average turnover days of P and K.
    Conclusions The cumulative decomposition rate of hairy vetch and straw were 81.93% and 51.65%, and it was 64.17% for their mixtures. Therefore, hairy vetch had higher release ratio than wheat straw in dry matter, C, N, P and K. In addition, the C, N, P and K had higher proportion in the easily decomposed part of hairy vetch than in wheat straws. The mixture of hairy vetch and wheat straw adjusted the nutrient proportion in the easily decomposed parts, and increased the average turnover days of C and N but decreased those of P and K, which was favorable to the use of subsequent crops.
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