Short-Term Benefits of Grain Legume Fallow Systems on Soil Fertility and Farmers Livelihood in the Humid Forest Zone of Cameroon

Abstract

Soil fertility management of smallholder farms in the humid tropics is a major issue as a result of inherently low fertility with nitrogen being the most limiting plant nutrient. Use of grain legume fallows could improve soil quality through nitrogen fixation and ensure food and nutritional security in developing countries. This field trial was laid out in a Randomized Complete Block Design (RCBD) to evaluate the short-term benefits of grain legume fallows (common bean, groundnut, cowpea, and soybean) on soil fertility improvement and income generation in relation to a natural weed fallow system. The results showed that total soil nitrogen content ranged from 0.19-0.24%, and differed (P < 0.001) significantly with the highest in common bean plots as compared to the others. The soil organic carbon (SOC) content was highest in cowpea plots (3.36 %) and lowest in the natural weed fallow (2.77 %). However, the SOC were not significantly different among the fallow systems but were higher than the SOC of the soil before sowing (2.41 %). Grain yield ranged from 1.0-1.9 t/ha and differed (P < 0.001) significantly. The highest profitability of integrating grain legumes in farming systems was recorded in the groundnut fallow, followed by soybean, and bean. Cowpea generated a negative return, while the natural fallow system had no effect. Integrating grain legumes fallow into agricultural systems in the humid tropics enhance the value of the fallow lands and may serve as viable short-term economic incentives for smallholder farmers. Contribution/Originality:This study contributes to the existing literature that reports the benefits of grain legumes on soil fertility improvement and also showed that the integration of grain legume fallows into agricultural systems in the humid tropics generate income for smallholder farmers and could serve as motivation for their adoption.

Contribution, Utilization, and Improvement of Legumes-Driven Biological Nitrogen Fixation in Agricultural Systems

“…The nutrient supply, such as nitrogen, is greater in improved fallow than in cropped land as the plants store nutrients from the air and bottomless layers of the soil, and falls their leaf litter to improve the soil and preserve moisture (Lemage and Tsegaye, 2020). Nanganoa et al (2019) indicated that different legume fallow systems had variable effects on the soil physicochemical properties of which the maximum distinguished effect is the total nitrogen content (ranging from 0.19 to 0.24%), organic carbon (SOC) content (ranging from 2.77 to 3.36%), and available phosphorus (ranging from 12.50 to 16.12 mg/kg) (Table 4).…”

“…Lemage and Tsegaye (2020) showed that abandoned agricultural land can be rehabilitated using improved legume fallow, which can enhance soil pH, organic carbon, available phosphorus, available potassium, and total nitrogen content. Besides this, Nanganoa et al (2019) indicated that different legume fallow systems had varying grain yield and economic benefits, ranging from enhanced soil nutrient contents, increased grain yield, and increased economic value of the fallow land. The authors revealed that grain yield ranging from 1.0 to1.9 t/ha can be obtained using different legume fallow systems with the highest in groundnut (1.9 t/ha), followed by soybean (1.6 t/ha), common bean (1.3 t/ha), and cowpea (1.0 t/ha) (Figure 4).…”

“…Additionally, developing countries experience the demand of more costs for synthetic fertilizer utilization although their use has adverse and unpredictable problems in the environment: mainly soil, water, and natural area contamination. Consequently, legumes increase soil fertility through the action of microorganisms, which are imperative to affect the soil properties, including soil biological, chemical, and physical properties (Stagnari et al, 2017;Nanganoa et al, 2019;Vasconcelos et al, 2020). The increasing attention of low-input crop production and sustainable agricultural systems from an environmental, economic, and managerial standpoint opened the door for sustained adoption and inclusion of legumes in the agricultural systems (Ghosh et al, 2007;Stagnari et al, 2017;Kebede, 2020b).…”

“…Full utilization of BNF and maximal benefit from BNF systems can be recognized through integrating legumes into agricultural systems in which the benefits of BNF can be extended to crops and cropping systems (Fujita et al, 1992;Stagnari et al, 2017;Kebede, 2020a). The well-known agricultural systems of integrating legumes into cropping systems include crop rotation, simultaneous intercropping, improved fallows, green manuring, and alley cropping (Ghosh et al, 2007;Meena et al, 2018;Nanganoa et al, 2019;Kebede, 2020a;Lengwati et al, 2020). Wider legume technology adoption and utilization, including methods that improve the BNF system and integrate it into agricultural cropping systems are imperative to enhance agricultural production.…”

The Common bean (Phaselous vulgaris L.) Response to Different Levels of Organic and Inorganic Fertilizers

“…Phaseolus vulgaris is an annual selfpollinated crop that belongs to the family of Fabaceae [5,6] and domesticated in Mesoamerica and Andes about 7000 years ago [5]. In developing countries common bean is very important in the nutrition of an increasing population where they deliver a fairly cheaper source of protein in the diet [7], fodder for animals [8] and source of elements for plant nutrition are the other benefits of common beans [9,10].…”