Semiarid producers recover degraded areas with organic fertilizer

Producers from municipalities in Ceará managed to recover degraded soils and increase productivity on small properties using fertilization with organic inputs. The simple and customized techniques, using inputs from within the gate, resulted in a 70% increase in the production of corn and beans in the municipality of Ibaretama. The result was observed over a period of five years, when three crops were harvested.

On another property, in Sobral, the area of ​​a spring that no longer supplied the community because it was degraded was recovered with a consortium of legumes and corn. The third experience took place in Irauçuba, in an area undergoing desertification, which is already showing signs of recovery. The experiments were carried out in Ceará and Embrapa researchers claim that similar results can be obtained in other states in the Brazilian Semiarid region.

Scientists explain that even in areas undergoing desertification, such as the municipality of Irauçuba (CE), the use of different low-cost strategies contributes to improving soil attributes, maintaining temperature and increasing fertility. . “A desertified area takes around 50 years to recover naturally, leaving it closed and unused. This is unfeasible, which is why we are working to recover the soil with the implementation of sustainable production systems”, explains agronomist Henrique Antunes, researcher at Embrapa Meio-Norte (PI).

The experiments by Embrapa researchers took place in three municipalities in Ceará: Ibaretama, Irauçuba and Sobral. In the municipality of Ibaretama, scientists worked in an area of ​​degraded Caatinga, with exposed soil and signs of erosion. Agricultural engineer Roberto Cláudio Pompeu, researcher at Embrapa Caprinos e Ovinos (CE), explains that the first layer of soil is the richest and easily washed away by rain if the soil is not protected, and that Agroforestry Systems (SAFs) are a alternative for improving these areas.

On the property in question, the implementation of the SAF was carried out with the species sabiá and cajá, intercropped with corn and beans. Animal manure and carnauba bagana were used as fertilizer and the result was a 70% increase in corn and bean production over a period of five years, when three crops were harvested.

Techniques accessible to all types of producers

The researchers then used a set of techniques accessible to any producer to implement SAFs in the Sítio Areias community, such as the intercropping of native plant crops in an area where there was an almost dry water source. Farmer Regina Souza (photo on the right), a local resident who actively participated in the project, states that the results are visible in the community. “Today we have planted native trees and other plants to feed the animals, as well as enough water to be enough for the animals and crops to consume.”

Pompeu explains that the cultivation of legumes can be used as a means of green manure rich in nitrogen, since farmers in the community do not usually apply fertilizers that favor the chemical attributes of the soil. “On the other hand, the corn-legumes consortium can also be an alternative for silage production, since the average dry matter content of the crotalaria-corn consortium at the time of harvest was 32,9%, the ideal range for the occurrence of adequate fermentation process, which did not happen with the corn-cunhã consortium.”

The results also indicated that the sunn hemp-corn consortium showed higher productivity than the wedge-corn consortium. In both cases, an average of 12,7% in crude protein content was observed, a number higher than the minimum content of 7% to meet the requirements in nitrogen compounds for the adequate functioning of the animals' rumen. This protein production can help reduce costs with purchasing protein ingredients and nitrogen fertilizers for the property.

The joint planting of corn and sunn hemp demonstrated, in general, better results in terms of productivity and quality of material for roughage production. For use as surface mulch in the soil, both consortia are interesting and a viable alternative to promote nutrient cycling in agroecological systems.

Inadequate soil management reduces productivity

Inadequate soil management and climatic factors are the main causes of degradation that, in some cases, compromise the area's productive capacity. High stocking rates and overgrazing, which occur when there are excess animals in the pasture, reduce herbaceous plants in addition to wearing down the area, sometimes irreversibly. Excessive trampling causes erosion with different degrees of intensity and progressively deteriorates soil and vegetation resources, reducing the fertility of the area by reducing the nutrients available to plants.

The removal of vegetation cover leaves the soil exposed to the force of rain, especially in the semi-arid region where rainy periods are short, but rainfall is intense and contributes to the erosion process. The researchers explain that the adoption of agroforestry systems or agroecological swiddens can be viable alternatives for recovering areas in the process of degradation, because the residue from trees maintained in the production system forms a layer of litter that contributes to the cycling of nutrients in the soil. Thus, the application of plant residues (twigs and leaves) to cover the soil is a strategy to increase sustainability, in addition to benefiting crops of economic interest, the soil and the environment.