The management of green cane harvest residues (RAC) and their maintenance on the ground generates many positive technical aspects for the cultivation of sugar cane. This was pointed out Patricia Digonzelli, researcher of the Agronomy team of the sugar cane of the Obispo Colombres Agroindustrial Experimental Station (Eeaoc).
Digonzelli explained that, in Tucumán, the amount of RAC that remains after the green harvest varies, generally, between 9 and 18 tons of dry matter per hectare. “This amount of RAC undergoes a decomposition process that is associated with temperature, rainfall and the time that elapses between two successive harvests, as very important factors, although not the only ones. Thus, at the time of the new harvest, between 45% and 65% of the RAC will have decomposed ”, he stressed.
He added that it is a residue of slow mineralization, because it has a high ratio of carbon and nitrogen (C / N). “Maintaining the RAC as a cover allows variable amounts of important elements, such as C, N and Potassium (K), to be returned to the agroecosystem,” he explained.
He added that in this way a recycling of nutrients is achieved, which in the medium and long term has effects on the physical and chemical fertility of the soil and could modify the fertilization schemes of the crop. In this aspect and according to the numerous experiences carried out, it was determined that at the end of each agricultural cycle, when the RAC coverage was maintained, between 3,500 and 8,000 Kg of C / ha, 10 to 100 Kg of N / ha returned to the system and 30 to 107 kg of K / ha. “Although the RAC of sugarcane contains interesting amounts of N, this will not be readily available for the crop since a process of immobilization of this occurs, therefore the benefit for the cane plantation will be given in the medium term”, said.
He also referred to the effect of coverage with RAC on the conservation of soil moisture. On this issue, he highlighted that maintaining the coverage with RAC improves the hydric condition of the soil, by improving the infiltration of rain / irrigation water and by reducing the evaporation of water from the soil. “In the conditions of Tucumán, where 90% of the sugarcane is cultivated in dry land and where the springs are dry, normally the canefield does not have enough water to satisfy its requirements during the sprouting and tillering phases. Due to this, the conservation of the RAC is an important tool to reduce the negative effect that the water deficit has on the growth of the cane field. This effect becomes more evident in the years when during the period of great growth of the cane fields (December to March) there are drought situations ”, he indicated.
As a counterpart of this, Digonzelli indicated that in those areas of the sugarcane area where excess humidity constitute a problem for cane production, maintaining the coverage with RAC will be counterproductive since it will aggravate the problem of excess humidity caused by the difficulties for the removal of surface water, the presence of a water table close to the surface and / or drainage problems. “In this situation, the RAC management must consider other solutions, such as its elimination from the lot by wrapping it to give it other destinations (for example, energy production) or the incorporation of the RAC in the soil profile,” he said.
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