Impact of growing maize (Zea mays) on the decomposition of incorporated fresh alfalfa residues
Authors: Muhammad, S.; Müller, T.; Mayer, J.; Joergensen, R.
Source: Biology and Fertility of Soils, Volume 43, Number 4, March 2007 , pp. 399-407(9)
Abstract:In this study, the effects of growing maize plants on the microbial decomposition of easily degradable plant residues were investigated in a 90-day pot experiment using a sandy arable soil. Four treatments were carried out: (1) untreated control, (2) with freshly chopped alfalfa residues (Medicago sativa L.) incorporated into soil, (3) with growing maize plants (Zea mays L.), and (4) with growing maize plants and freshly chopped alfalfa residues incorporated into soil. The amount of alfalfa residues was equivalent to 1.5 mg C g−1 soil and 120 g N g−1 soil. At the end of the experiment, only the combination of growing maize plants and alfalfa residues significantly increased the contents of microbial biomass C, microbial biomass N, and ergosterol in soil compared to the non-amended control. The dry weight of the maize shoot material was more than doubled in the treatment with alfalfa residues than without. In treatment (2), 6% of the alfalfa residues could be recovered as plant remains >2 mm. In treatment (4), this fraction contained 14.7% alfalfa residues and 85.3% maize root remains, calculated on the basis of 13C values. This means that 60% more alfalfa-C was recovered than in treatment (2). The reasons for the retardation in the breakdown of alfalfa residues might be water deficiency of soil microorganisms in the increased presence of maize roots. Assuming that the addition of alfalfa residues did not affect the decomposition of native soil organic matter, only 23% of the alfalfa residues were found as CO2 monitored with a portable gas analyzer with a dynamic chamber. The discrepancy is probably due to problems in measuring peak concentrations of CO2 evolution in the two alfalfa treatments at the beginning of the experiment and in the two maize treatments at the end, especially in treatment (4).
Document Type: Research Article
Affiliations: Email: firstname.lastname@example.org
Publication date: March 2007