| Autor: |
Ogoke, I.J., Carsky, R.J., Togun, A.O., Dashiell, K. |
| Zdroj: |
Biological Agriculture and Horticulture; January 2002, Vol. 20 Issue: 2 p133-142, 10p |
| Abstrakt: |
ABSTRACTThis study was carried out to assess the carbon returned in soyabean crop residues as a function of soyabean maturity class and P fertilizer. Three levels of P were applied to four soyabean varieties in three replications at four sites. Late varieties gave greater root + litter C input than early and medium varieties, and their responses to P were larger. P application increased root + litter C by 44–49%, and total C, comprising C in soyabean root, litter and stover, by 45–46%. Root + litter C was 60% of total C input by soyabean. While soyabean was not able to maintain soil organic C (SOC) at an annual C input decomposition rate of 70%, the application of P provided 105–107% of the C input required to maintain SOC at 5.1 g kg−1at C input decomposition rate of 50%. For the low SOC levels of 5.1–8.7 g kg−1at the sites, it was estimated that total C inputs of 12.2–14.2 Mg ha−1are required to increase organic C by 1 g kg−1. Depending on decomposition rate, however, total C input by the varieties was 7–22% of total C required to increase organic C by the same amount. Although the late varieties responded positively to P, the total C required to increase organic C by 1 g kg−1was reduced by only 4–10% with the application of P. Organic C input by soyabean in a cereal-based cropping system remains minimal despite increased soyabean duration and the application of P. |
| Databáze: |
Supplemental Index |
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