Produção agrícola irrigada da região do médio curso do Rio Paraíba e os riscos climáticos.

Abstract

Proper use of soil is the first step towards sustainable agriculture and to achieve this, soil management must be used in accordance with its carrying capacity and economic productivity. The present research aimed to carry out, for the hydrographic basin of the middle course of the Paraíba River, the evaluation and mapping of the potential for irrigated agricultural production and climate risks through the identification of rural areas, their soil restrictive factors, the potential for irrigation and land expansion and their suitability for crops. A 109-year rainfall data series was obtained and kriging and geospatial analysis was performed. The Agricultural Zoning of the State of Paraíba and municipal indicators of irrigated and fertigated areas were used, as well as the database of the Brazilian Institute of Geography and Statistics for the crops of beans, cassava, corn, sorghum, and palm. The Agricultural Zoning of Climate Risk was developed, mapping the types of soils with water retention capacity. Maps of the climatic conditions for the crops, irrigation potential and water retention capacity, and irrigated agricultural production potential for the crops were prepared. The most frequent land use restriction factors were texture, effective depth and stoniness in the strong class, followed by erodibility, slope and fertility in the moderate class. The land suitability for irrigation followed the proportion of special use < arable land with restricted suitability < non-arable land. Areas of additional irrigated expansion were identified in the municipalities of Boqueirão and Aroeiras. Agricultural areas were identified in 21.42%, with temporary crop planting in 12.25%, and with 1,702 ha irrigated. The identified productive areas followed the proportion of sorghum < cassava < pumpkin < corn forage < fava bean < forage sorghum < forage cactus < corn < common bean. Recommended areas regarding soil water storage capacity identified in lands followed the proportion of type 1 < 3 < 2 < prohibited areas. The crops of beans and sorghum were indicated in the Agricultural Zoning of Climatic Risk for soil types 1, 2 and 3 in the 3 groups, for all municipalities; cassava and forage palm recommended only for the municipalities of Itatuba and Umbuzeiro; corn with the exception of the municipality of Umbuzeiro for soil type 1. Areas recommended for irrigation followed the proportion of low < middle < very low class. The potential for irrigated agricultural production for the crops followed the proportion in area, beans VH and H < L < M < VL; cassava VH and H < M < L < VL; corn VL at 100%; forage palm L < M < VL; sorghum VH and H < M < L < VL. The greatest limitations observed were due to the water requirements of the crops and, to some extent, to the predominant soils in the area. Irrigation may be carried out as long as it is used from natural or artificial reservoirs, due to the lack of water security in the region. Since it is a relatively complex activity, irrigation must be disseminated through a coordinated and systematic action, taking into account the areas suggested in this research. In the case of improving water deficiency for irrigation, it is recommended to adjust the planting and cultivation period of crops to the rainy season; select crops and cultivars that are best adapted to the lack of water; use of practices that ensure maximum water retention in the soil, such as incorporation of plant remains and soil cover, ensuring maximum infiltration and minimum evaporation.