Above-ground biomass, nutrients, and persistence of an early and a late maturing Mucuna variety in the Forest–Savannah Transitional Zone of Ghana

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• 作者：Jü ; rgen Anthofer and Jü ; rgen Kroschel
• 关键词：Cover crop ; Fallow ; Biomass ; N₂ fixation ; Nutrient uptake ; Ground cover
• 刊名：Agriculture ; Ecosystems & Environment
• 出版年：2005
• 期刊代码：6_01678809
• 类别：abs
• 出版时间：2005
• 卷：110
• 期：1-2
• 页码：59-77
• 文件大小：459 K

摘要

Many farmers in West Africa have adopted the herbaceous legume, Mucuna pruriens, as a fallow species to control weeds and to increase soil fertility on crop lands. This paper presents the biomass, nutrient content, and persistence results of farmer managed trials with late maturing M. pruriens var. utilis (L.) D.C. and an early maturing unclassified Mucuna cultivar relative to a short season natural fallow (control). From August until December 1998 and from June 1999 until March 2000, research was conducted at different farm locations in the Forest–Savannah Transitional Zone and in the Guinea Savannah Zone of Ghana. The following parameters were evaluated: (1) accumulation of above-ground Mucuna biomass during the short rainy season; (2) atmospheric N₂ fixation during the same period; (3) Mucuna seed yield components; (4) persistence of above-ground Mucuna and natural fallow biomass throughout the dry season; (5) nutrient concentration and nutrient accumulation of Mucuna and natural fallow at the beginning and the end of the dry season; and (6) percentage ground cover by various biomass components throughout the dry season. During the first 2 months of establishment, M. pruriens grew slowly, producing 163 kg ha⁻¹ above-ground biomass after 30 days and 1472 kg ha⁻¹ after 60 days, but produced 4003 kg dry matter ha⁻¹ after 90 days. Atmospheric nitrogen (N₂) fixed by late maturing M. pruriens was estimated at 107.7 kg ha⁻¹ but only 46.1 kg ha⁻¹ for the early maturing Mucuna cultivar. The estimated amount of N₂ fixed was significantly correlated with the amount of Mucuna biomass produced with R² = 0.75 for the early maturing cultivar and R² = 0.69 for M. pruriens. The nutrient uptake of macronutrients other than N in the Mucuna fallow did not differ significantly from that of the natural fallow treatment for either cultivar. Following a linear regression model, total above-ground biomass on M. pruriens plots declined by 503 kg ha⁻¹ every 4 weeks from November until March, while the biomass on plots planted with the early maturing Mucuna cultivar declined by 911 kg ha⁻¹. While ground coverage (including weeds and crop residues) on fields planted with M. pruriens was still 89.7%at the end of the dry season, coverage on fields planted with the early maturing Mucuna variety averaged only 72%.

It was concluded that late maturing Mucuna varieties planted as a relay intercrop in maize (Zea mays) in June can be more easily integrated into existing farming systems than early maturing ones planted in August/September because Mucuna planting does not compete with other farming activities but can be combined with the second weeding of maize. Moreover, it is suggested that the major advantage of a Mucuna fallow is based on the option of not having to burn vegetation in preparation for the next cropping season. The few emerging weeds can be easily slashed as compared to a natural fallow which produces large amounts of lignified plant material. Therefore, this slash-and-mulch technology leads to reduced nutrient losses.