Biological nitrogen fixation by pigeon pea and cowpea in the doubled-up and other cropping systems on the Luvisols of Central Malawi

Abstract

Legumes form a very important component in Malawi's cropping systems because of their roles in food security, income generation and soil fertility improvement through biological nitrogen fixation (BNF). They are commonly grown in various cropping systems including sole cropping, cereal-legume intercrops and legume-legume intercrops (also commonly referred to as "doubled-up"). However, information on BNF by the pigeon pea and cowpea under doubled-up system is scanty. Therefore, a study was conducted at two sites of Lilongwe and Dowa in the 2013/14 growing season, to quantify and compare the amounts of biologically fixed nitrogen in the three legume cropping systems. The experiments were laid out in a randomized complete block design and BNF was estimated using the modified nitrogen difference method. Results showed that there were significant differences (P < 0.05) in nodule numbers, nodule dry weights, and quantities of N 2 fixed per unit area due to cropping systems' effects at both sites. Sole cropped pigeon pea produced the highest N 2 fixed (92.9 kg N ha ) by 33%. From this study it can be noted that all three legume cropping systems can lead to substantial amounts of biologically fixed nitrogen, but their implementation should consider both combinations and environmental factors for specific sites.

The role of women empowerment and labour dependency on adoption of integrated soil fertility management in Malawi

“…The positive influence on the decision to grow legumes is supported by the long-standing view that legumes, including groundnuts, are 'women crops' (Nakazi et al, 2017;Orr, Kambombo, Roth, Harris, & Doyle, 2015). Although our results support this, other findings in the region show that for the main legume grown in the area, groundnuts, households headed by women tend to allocate less land to it and are 20% less productive (Joe-Nkamuke et al, 2019) than their maleheaded counterparts.…”

“…When they enter the market and become profitable, they shift status from being subsistence to commercial. Then, men's participation increases but largely relies on women's knowledge for efficient management (Nakazi et al, 2017). However, the inclusion of women's role using WEAI even in male-headed households and its influence on both, the probability to grow legumes and their productivity, requires further scrutiny.…”

“…In these nitrogen-limited soils and under low input farming, the nitrogen fixed by legumes is being explored and promoted as one of the major sources of the nutrient (Njira, Semu, Mrema, & Nalivata, 2017). There has been increased F I G U R E 1 Maize productivity trends between 1992 and 2019: maize yield (ton ha −1 ), quantity of fertilizer (megatons) applied to maize and the fertilizer subsidy (megatons).…”

Spatial Arrangements on Growth and Yield of Cowpea (<em>Vigna unguiculata L. Walp.</em>) in Intercropping

“…It was observed that there was a significant difference (P<0.01) in total number of nodules per plant at each WAP (table 6). Njira et al (2017) reported that number of nodules in pigeon pea was reduced when intercropped with cowpea. Further, Njira et al (2017) noted that, this may be due to the competition for resources when intercropping legume -legume or legume -cereals.…”

“…Njira et al (2017) reported that number of nodules in pigeon pea was reduced when intercropped with cowpea. Further, Njira et al (2017) noted that, this may be due to the competition for resources when intercropping legume -legume or legume -cereals. Number of nodules increased with increasing row spacing [Banik et al, 2006].…”