Yield gaps in intensive rice-maize cropping sequences in the humid tropics of Indonesia

Abstract

Multiple crops can be grown sequentially on the same field within a 12-month period in tropical humid environments. Yield gap analysis focusing on both individual crop cycles and cropping systems can help identifying opportunities to increase annual productivity. Indonesia was used as a case study to evaluate options for increasing annual productivity in rice and maize through closure of existing yield gaps at both crop-cycle and cropping-system levels. A total of 31 (rice) and 11 (maize) sites for irrigated crops, and 24 (rice) and 29 (maize) sites for rainfed crops were selected based on their share of national harvested area. Crop modeling based on local weather, soil, and management data, together with average farmer yield data, were used to estimate yield potential and yield gaps for individual crop cycles (total: 367) and cropping systems (total: 154). Extra rice and maize production potential were estimated for different scenarios of crop intensification and/or cropland expansion and compared against projected increase in grain demand for the two crops by year 2035. Yield gaps were substantially larger in maize versus rice and, in the case of rice, yield gap was larger in rainfed lowland versus irrigated conditions. At national level, average farmer yield for irrigated rice and maize represented 63% and 44% of their respective yield potential (9.5 and 13.6 Mg ha−1) while, in rainfed conditions, average farmer yield was 52% (rice) and 42% (maize) of respective water-limited yield potential (9.2 and 12.2 Mg ha−1). Scenario assessment indicated that Indonesia can produce an extra 24 and 16 million metric tons (MMT) of rice and maize annually (respective 31 and 67% increase relative to current production) and reach near self-sufficiency for both crops on existing cropland area by closing current yield gaps to a level equivalent to 80% of yield potential (irrigated crops) or 70% of water-limited yield potential (rainfed crops). Analysis of cropping-system yield gaps indicated an additional potential increase in annual rice (3 MMT) and maize (11 MMT) production derived from adoption of crop sequences with highest annual yield potential combined with yield gap closure, though this may be limited by extra input requirements and/or increasing risk. Findings from this study demonstrate the utility of yield-gap analysis to estimate extra crop production potential derived from intensification at both individual-crop and cropping-systems levels.