Increasing profits and reducing climate risk through irrigation management for cassava farming in Northeast Brazil

Abstract

Cassava is an important crop in almost all tropical countries. Its roots are used in several ways as food and industrial raw material. Its relevance for worldwide food security is due to its capacity to yield on marginal areas where most crops do not even grow. Also, the energy production potential is high and comparable to other major crops, which makes cassava suitable for smallholder agriculture in developing countries. However, the worldwide actual yield remains at least three folds lower compared to reported potential yield. Cassava research efforts should focus on finding important factors for low yield and management practices to increase it. As a common alternative to increase crop yield, irrigation can be used. Although the latter is not commonly applied to cassava production, promising results can be found in the literature. The present research used the MANIHOT-DSSAT cassava model to assess possible cassava response to alternative planting dates associated with irrigation. Simulations reproducing traditional rainfed cassava management – plantings at recommended dates – were used as a reference scenario. Then, a new set of simulations were done using alternative planting – plantings on non-recommended dates – and irrigation. Both sets of simulations were done for 36 years of Araripina – PE (7º 34’ S, 40º 29’ W), Laje – BA (13º 10’ S, 39º 25’ W) and Lagarto - SE (10º 55’ S, 37º 39’ W) climate data. The irrigation treatments consisted of 100, 80, 60, 40 and 20% of required water during the season. Yield results at different harvest times were obtained to observe the influence of harvest anticipation. The simulation results were used for the economic analysis, which was divided into two: annual and long-term. For the annual analysis, only operational costs were considered and the indicator used was the gross margin. For the long-term analysis, no cost was left out and a period of 10 years was considered. The yield value used were the 20, 30 and 40% percentile and sell prices were not kept constant. The long-term indicator was the net present value (NPV). For the traditional management scenario, higher yields were obtained for plantings at the start of the wet season with different cycle lengths. For the alternative scenario, Araripina showed the highest yield increase compared to the reference scenario, followed by Lagarto (21.3%) and Laje (8%). In general, the less stressful irrigation treatments were responsible for the highest yield values. The long-term economic analysis showed that the use of irrigation in the three regions is a viable investment in most cases. However, the benefit of the irrigation is higher only at Araripina. Then, the proposed management is not a worthwhile investment for farmers at Laje and Lagarto.