Sugarcane Straw Blanket Management Effects on Plant Growth, Development, and Yield in Southeastern Brazil

Abstract

In Brazilian sugarcane (Saccharum spp.) production systems, the practice of moving harvesting residue from row to inter‐row positions (i.e., raking) has increased in response to producer concerns over the potential negative effects of sugarcane straw on crop establishment and stalk yield. Despite increasing adoption among sugarcane farmers, the impacts of straw raking practices on plant growth and yield remain unclear. A 2‐yr experiment that included both dry and wet seasons was conducted at two sites in southeastern Brazil to evaluate straw management strategy effects on plant tillering, phytomass accumulation, plant nutritional status, and stalk yield. The experiments were established at the Bom Retiro mill and the Univalem mill. Experimental treatments included raking straw to inter‐rows (raked), total straw removal (bare soil), and no straw removal (straw cover). Raked and bare soil treatments improved plant tillering but did not influence final plant population. Straw management had a slight effect on phytomass accumulation. Reduction of phytomass yield was observed from the first to the second ratoon during both seasons at both sites. At Bom Retiro, phytomass yield decreased 37% for stands established during the dry season and 19% for stands established during the wet season. At Univalem, phytomass yield decreased 20% for stands established during the dry season and 30% for stands established during the wet season. Retaining straw in the field (regardless of treatment) increased leaf tissue P content but not stalk yield. Raking straw from row to inter‐row positions at these locations in southeastern Brazil had no benefit on sugarcane yield but may result in soil compaction and higher production costs over time.

Changes in soil temperature and moisture due to sugarcane straw removal in central-southern Brazil

“…In Brazil, other authors have reported reductions of 0.01 and 0.08 g g -1 due to straw removal (Peres et al, 2010;Awe et al, 2015;Corrêa et al, 2019). Our data is also in line with previous simulations performed by Gmach et al (2019), who estimated that the complete maintenance of straw (12 Mg ha -1 ) or even partial maintenance (6 Mg ha -1 ) delays the water-limiting condition in plants for approximately one month compared to bare soil (total removal) during the dry season in the state of São Paulo. However, even an increase of 0.03 g g -1 in soil moisture noted in medium soil represents a gain of about 64 L m 2 (four-day water supply for the crop).…”

“…This improvement would be associated with: i) greater heating of the soil without straw; ii) increase in the intensity and amount of solar radiation that reaches the sugarcane ratoon; iii) removal of the physical barrier formed by the straw left on the sugarcane ratoon. All these effects induced the sugarcane sector to adopt the raked (raking straw to inter-rows) practice, which recently discovered that, despite providing these benefits in the initial period of plant development, failed to generate increases in productivity (Lisboa et al, 2019).…”

Straw Removal Effects on Sugarcane Root System and Stalk Yield

“…These conditions potentially improve plant growth and, consequently, phytomass yield. Although we strongly recognize that it is mandatory to consider specific edaphoclimatic conditions to perform sustainable straw removal, our findings provide relevant understanding about why moderate straw removal has been suggested in several studies in which straw removal management was framed [15,24,55,57].…”

“…However, straw maintenance higher than 10 Mg ha −1 is also associated with a reduction in plant sprouts, stalk yield [24,25] and sucrose concentration in stalks [56], particularly in the region where the study was conducted, which is cooler than other sugarcane-producing regions in Brazil [25]. Overall, decreasing of initial sugarcane phytomass yield (tillering) occurs even under lower quantities of straw; this is especially remarkable under cooler regions [24], but in most cases, the crop is able to recover from the negative impacts caused by straw retention in earlier growth stages [15,24,57].…”