Sugarcane yield response to rainfall partitioning and irrigation in contrasting cropping environments1

Abstract

Most sugarcane (Saccharum officinarum L.) in Brazil is produced through rainfed cropping, but several methods and management irrigation approaches coexist in some mills, creating different cropping environments. This work aimed to analyze the relationship between rainfall and sugarcane yield when cultivated in cropping environments with a high gradient in terms of water supply. A dataset of physical yield and agro-industrial characteristics was analyzed from a time series of 21 crop cycles. The cropping environments were categorized according to relief conditions in the landscape and the level of water supply for sugarcane cultivation: 1) hillside without irrigation; 2) rainfed tableland; 3) tableland with so-called “crop-saving irrigation”; 4) tableland irrigated by a linear moving irrigation system; 5) floodplain; and 6) tableland irrigated by a subsurface drip system. The total precipitation of the sugarcane cropping cycle was not a good yield predictor. For rainfed environments, summer rainfall resulted in the most positive correlations with sugarcane yield and an average increase of 53.2 kg ha-1 mm-1, a value similar to that of the saving irrigated and linear moving irrigated environments, with 54 and 57 kg ha-1 mm-1, respectively. In cropping environments with high frequency irrigation, the average increment was 17.6 kg ha-1 mm-1. In the rainfed and saving irrigated environments, cultivars RB92579 and CO997 stood out with the highest (91.3 kg ha-1 mm-1) and lowest (43.6 kg ha-1 mm-1) average increases, respectively. For rainfed cropping environments and drier summers, sugarcane yield losses could reach 21% compared to crop seasons with wetter summers.