Abstract
The sugarcane (Saccharum spp. L.) mechanical harvesting system leaves a large amount of straw mulch on the soil surface. The straw mulch may affect soil conditions, root regrowth, and sugarcane yield. Thus, this study assessed the response of sugarcane root system growth and stalk yield to different rates of straw removal. An experiment was conducted in a Rhodic Kandiudox with sand clay loam texture to test the impact of four rates of straw removal: no removal (18.9 Mg ha−1 of dry mass); moderate removal (8.7 Mg ha−1); high removal (4.2 Mg ha−1) and total removal on sugarcane root system and stalk yield. Higher concentrations of roots (60%) were found in the first 40 cm of soil. Moderate straw removal resulted in higher root mass (3.6 Mg ha−1) and stalk production (23 Mg ha−1 of dry mass). However, no straw removal reduced root mass by <40% (2099 kg ha−1) and reduced stalk yield by >20% (105 Mg ha−1). Through regression analysis, it was estimated that retaining between 8.5 and 13 Mg ha−1 of straw resulted in the highest root mass and stalk yield. Managing straw removal to retain a moderate amount enables producers to sustain suitable soil conditions for sugarcane root growth and stalk production while providing straw for industrial use.
Highlights
Brazil is the world’s largest sugarcane producer, accounting for about 40% of global production, with 643 million tons of stalks harvested across 8.5 million hectares during the 2019/2020 harvesting season, mainly concentrated (90%) in the south-central region of the country [1]
As the sampling points neared the plant growth row, a larger root mass was measured, with the highest values occurring at points in the crop inter-row
Different rates of straw removal did not affect (p > 0.05) the sugarcane root:shoot ratio, with values from an Oxisol field cultivated with sugarcane in Capivarí, São Paulo (SP), Brazil
Summary
Brazil is the world’s largest sugarcane producer, accounting for about 40% of global production, with 643 million tons of stalks harvested across 8.5 million hectares during the 2019/2020 harvesting season, mainly concentrated (90%) in the south-central region of the country [1]. This production results in 35 million of tons of sugar and 32 billion liters of ethanol [1]. Bagasse from sugarcane-milling processes, plus straw (i.e., dry and green leaves) have an essential role in bioelectricity co-generation and second-generation ethanol production [2,3]. Straw mulching provides several agronomic benefits for the soil–plant system, among them being: increased soil protection against erosion processes [3,7], enhanced soil organic matter content [8,9], improved nutrient cycling [10], Agronomy 2020, 10, 1048; doi:10.3390/agronomy10071048 www.mdpi.com/journal/agronomy
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