Optimizing soil nitrogen balance in a potato cropping system through legume intercropping

Abstract

Negative nitrogen balance represents a major factor causing low potato yield in potato growing areas of Kenya while its excessive surplus poses a significant environmental concern. In order to synchronize this tradeoff, a field trial integrating potato (Solanum tuberosum L.) with lima bean (Phaseolus lunatus L.) and dolichos (Lablab purpureus L.) in intercropping system was conducted in the upper midland [1552 m above sea level (masl), lower highland (1894 masl) and upper highland (2552 masl)] agro-ecological zones of Kenya. Nitrogen gains from mineralization, fertilization, biological fixation, and outputs from biomass accumulation, leaching, volatilization and soil erosion were quantified using standard procedures. Soil N balance ranged from-10.7 to-18.1 kg N ha-1 for sole potato, 4.1 to 6.6 kg N ha-1 for intercropping and 2.9 to 22.3 kg N ha-1 for sole legumes. The intermediate range of polyphenol and lignin contents in intercropping enhanced N mineralization with peak N release of 8 to 9 kg N ha-1 matching with peak N uptake by potato (19.9 to 31.2 kg N ha-1). Nitrate was leached below the active root zone in sole potato cropping (4.2 to 46.6 kg N ha-1), a process that was diverged by the Electronic supplementary material The online version of this article (

Response of potato crop to selected nutrients in central and eastern highlands of Kenya

“…The response of potato crop to the omission of N was imminent as indicated by uptake and yield parameter results, portraying N as the most limiting nutrient in potato-growing areas of Kenya. Nitrogen as one of the major nutrients is responsible for key plant process that influences the growth and yield of potato (Lamb et al, 2014) continually farmed which results in lots of N mining as well as losses through erosion and leaching (Gitari et al, 2019;Nyawade et al, 2020). Similar results have been reported from multi-location trials on different soil types, in several African countries including Kenya (Kihara et al, 2016).…”

“…Farmers underfertilize the farms due to a complex of factors such as limited knowledge of soil status, high cost of fertilizers, poor quality manure, limited options on available fertilizer types, as well as low returns on investment in fertilizer application due to possible unresponsive soils (Bindraban et al, 2018;Fairhurst, 2012;Gildemacher, Demo et al, 2009). In addition, there could be unbalances of soil nutrient, which in turn affects the nutrient uptake, thus affecting crop response to nutrient additions (Gitari et al, 2020;Nyawade et al, 2020).…”

Intercropping—Evaluating the Advantages to Broadacre Systems

“…Other reported benefits of intercropping include reduction in pest and disease infestation [24,25], increase in soil organic matter, earthworm and soil microbial activity and improvement in soil structure [26][27][28][29]. Furthermore, incorporating legumes in intercropping promotes nitrogen fixation and improves soil fertility [30,31]; growing crops with different root depths further enhances the efficient use of below-ground resources [32,33]. On-farm crop diversification through intercropping can enhance the outputs and stability of agricultural production in the face of seasonal variability and changing climates [24,34].…”

Chlorophyll meter‐based leaf nitrogen status to manage nitrogen in tropical potato production

“…However, potato plants require an adequate supply of N throughout the cycle to achieve optimum tuber yield (Fernandes, Soratto, & Silva, 2011;Giletto & Echeverría, 2013a;Koch et al, 2020;Rens et al, 2015;Souza, Soratto, Sandaña, Venterea, & Rosen, 2020a;Sun et al, 2012). Moreover, because of the inherent shallow potato root system (Nyawade et al, 2020), conventional N fertilization may result in N losses, compromising crop N recovery (Bero, Ruark, & Lowery, 2014;Errebhi, Rosen, Gupta, & Birong, 1998;Giletto & Echeverría, 2013b;Nyawade et al, 2020).…”