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Article

Rice Yield Gaps in Smallholder Systems of the Kilombero Floodplain in Tanzania

1
Institute of Crop Science and Resource Conservation (INRES), University of Bonn, 53115 Bonn, Germany
2
Africa Rice Center (AfricaRice), P.O. Box 1690, Antananarivo 101, Madagascar
*
Author to whom correspondence should be addressed.
Agronomy 2020, 10(8), 1135; https://doi.org/10.3390/agronomy10081135
Received: 30 June 2020 / Revised: 30 July 2020 / Accepted: 31 July 2020 / Published: 5 August 2020
(This article belongs to the Special Issue Organic vs. Conventional Cropping Systems)
To meet the growing rice demand in Africa, gaps between actual and attainable yields have to be reduced. In Tanzania, this particularly concerns smallholder rain-fed production systems in the floodplains. After quantifying the existing yield gaps, key contributing factors need to be analyzed to improve site-specific management. Field experiments were conducted for three years and in three pedo-hydrological environments (fringe, middle, and center positions) of the Kilombero floodplain to evaluate: (1) The grain yield under farmers’ management (actual yield), (2) yield with the best-recommended management (attainable yield), and (3) the non-limited yield simulated by the APSIM model (potential yield). In the field, we additionally assessed incremental effects of (1) field bunding and soil levelling, (2 and 3) additionally applying of 60 kg N ha−1, as urea or as farmyard manure (FYM), and (4 and 5) incorporating in-situ-grown leguminous green manures. Attainable yields were determined with mineral N application at 120 kg ha−1, additional PK fertilizer and supplemental irrigation. On average across years and positions, the potential, the attainable, and farmers’ actual yields were 11.5, 8.5, and 2.8 t ha−1 indicating a high total yield gap. About 16–38%, 11–20%, and 28–42% of this gap could be attributed to non-controllable yield-reducing (i.e., pest and diseases), yield-limiting (i.e., water and nutrient deficiencies), and yield-defining factors (i.e., poor soil and crop management), respectively. Results indicate a closure of the exploitable yield gap (differences between attainable and farmers’ actual yields) by up to 6.5 t ha−1 (nearly 60% of the potential yield). This exploitable yield gap was larger in 2016 than in 2017. Also, the gap was larger in the water-limited fringe and middle than in the frequently submerged center positions. Simple field bunds combined with land levelling could close 15–35% of the exploitable yield gap, depending on field positions and year. FYM or green manures were less effective than mineral N; however, in 2017 and in the wetter middle and center positions, they reduced the yield gap by >50%. We conclude that yield gaps in rainfed rice in Kilombero floodplain are large, but that a site- and system-specific adaptation of crop management can close much of the exploitable yield gap and increase grain yields by 0.7–4.8 t ha−1. Similar benefits may be obtained in other hydrologically variable floodplain environments of the region and beyond. View Full-Text
Keywords: APSIM; farmyard manure; green manure; mineral N; yield potential APSIM; farmyard manure; green manure; mineral N; yield potential
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MDPI and ACS Style

Kwesiga, J.; Grotelüschen, K.; Senthilkumar, K.; Neuhoff, D.; Döring, T.F.; Becker, M. Rice Yield Gaps in Smallholder Systems of the Kilombero Floodplain in Tanzania. Agronomy 2020, 10, 1135. https://doi.org/10.3390/agronomy10081135

AMA Style

Kwesiga J, Grotelüschen K, Senthilkumar K, Neuhoff D, Döring TF, Becker M. Rice Yield Gaps in Smallholder Systems of the Kilombero Floodplain in Tanzania. Agronomy. 2020; 10(8):1135. https://doi.org/10.3390/agronomy10081135

Chicago/Turabian Style

Kwesiga, Julius, Kristina Grotelüschen, Kalimuthu Senthilkumar, Daniel Neuhoff, Thomas F. Döring, and Mathias Becker. 2020. "Rice Yield Gaps in Smallholder Systems of the Kilombero Floodplain in Tanzania" Agronomy 10, no. 8: 1135. https://doi.org/10.3390/agronomy10081135

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