Short-term crop rotation interactive effects on soil microbial communities and potato yield under field conditions

Abstract

Introduction The inclusion of plant-parasitic nematode ( Meloidogyne species) non-host crops in potato ( Solanum tuberosum L.) -based cropping systems can sustainably manage the pest and reduce the application of greenhouse gas-emitting agro-chemicals. Nevertheless, there exists a research gap on how these cropping systems interact with soil microbiome. Methods A 2-year field study was conducted at the University of Limpopo and the Agricultural Research Council to investigate the effects of potato monoculture, Cucumis africanus -potato, sorghum-potato and potato (Velum)-potato cropping sequences on soil health and tuber yield. The treatment crops, namely, sweet stem sorghum ( Sorghum bicolor ) cv. ′Ndendane-X1′, C. africanus , potato cv. ′Mondial G3′ and potato cv. ′Mondial G3′-velum (control), were assigned to 4 m 2 subplots in Sequence 1, in a randomized complete block design, with six replicates. The successor potato crop was planted in Sequence 2. Crop arrangement in Sequences 3 and 4 was as in Sequences 1 and 2, respectively. Soil organic carbon content, enzyme activity, nematode and bacterial functional diversity data were collected from Sequences 1 to 4. Final potato tuber yield was recorded in Sequence 4. Results Based on the results, nematode indices revealed disturbed agroecosystems dominated with bacterial decomposition pathways, which is a common occurrence in intensively managed soils. High soil organic carbon content, microbial diversity and enzyme activity were observed in sorghum-potato and C. africanus -potato compared to potato monoculture (with or without velum), at both locations. In addition, sorghum-potato improved soil structure over time based on the nematode faunal results, thereby depicting its ability to promote soil health compared to other cropping systems. Tuber yield mass significantly varied ( p ≤ 0.05) among cropping sequences at both locations with potato (Velum)-potato and C. africanus -potato sequences recording higher yields than potato monoculture or sorghum-potato. Discussion Crop diversification increased soil organic carbon content, microbial diversity and enzyme activity. Overall, sorghum-potato effectively improved soil health and soil structure over time, better than the other cropping systems.