No abstract

The wide adoption of highly productive soy–maize double cropping has allowed Brazil to become one of the main producers and exporters of these commodities. However, land cover and climate change could affect the viability of double cropping due to a shortening of the rainy season, and both crops could be affected. The goals of this study were to evaluate if adaptation measures such as adoption of shorter-cycle cultivars and delaying sowing dates are effective to maintain soybean and maize yield in the main producing regions in Brazil. We used a crop model and four climate models to simulate double cropping in two climate scenarios that differ in Amazonia and Cerrado deforestation levels. We tested if 10 soybean and 17 maize sowing dates and three cultivar combination could reduce the impacts of a shorter rainy season in double cropping yield and gross revenue. Results showed a decrease in maize yield due to a delay of soybean sowing dates and rainfall reduction during the growing season. Adaptation through delaying sowing dates and the adoption of short cycle cultivars was not effective to maintain system revenue in all the study regions in a scenario with high deforestation levels.

In order to assist in high-yield agricultural management in multiple cropping systems, it is essential to understand the link between the rainy season onset and crops sowing dates, since it considerably affects the management, yield and output. We built crop calendars derived from remote sensing products and investigated the link between sowing dates and the onset of the rainy season in irrigated and rainfed agriculture in Western Bahia, a new and important agricultural frontier in Brazilian Cerrado. Crop sowing dates were obtained from green-up dates from 2001 to 2019. Rainy season onset dates were determined using CHIRPS daily precipitation data. Results indicate that sowing occurs from 26 October to 15 November and the rainy season starts from 17 to 27 October. Rainfed sowing dates are strongly correlated to rainy season onset and are particularly affected in years where rains are delayed. Sowing dates in irrigated pixels occur up to 25 days earlier than rainfed and are not correlated to rainy season onset. Irrigated farms are sowing earlier and in a shorter window than rainfed, with a stronger resilience in years where rains are delayed, and have adapted their sowing operation towards a more intensive agriculture and efficient water use during the rainy season.