Dissertação
Balanço hídrico do solo e partição da evapotranspiração de soja, milho e feijão submetidos à irrigação deficitária no Sul do Brasil
Fecha
2016-01-07Registro en:
ÁVILA, Viviane Schons de. Soil water balance and evapotrasnpiration partitioning for soybean, maize and beans under deficit irrigation in Southern Brazil. 2016. 90 f. Dissertação (Mestrado em Engenharia Agrícola) - Universidade Federal de Santa Maria, Santa Maria, 2016.
Autor
Ávila, Viviane Schons de
Institución
Resumen
In order to overcome periods of drought and low water availability, deficit irrigation becomes
an important tool as long as it is applied on the least sensitive periods of the crops development to reduce
the impacts on the productivity. Furthermore, deficit irrigation can be most efficient when there is an
understanding of the way plants lose water. Crop evapotranspiration (ETc) is divided into soil
evaporation (Es) and crop transpiration (Tc). The objectives of this paper were, beside measuring the soil
water balance for different crops (bean, soybean and maize), was to determine adequate crop base
coefficients (Kcb) for southern Brazil conditions, partition ETc into Es and Tc to better evaluate and
understand soil water dynamics along the crops development cycle, determine water productivity (WP)
considering different levels of deficit irrigation, to compare scenarios of water consumption on main
and secondary crop schedules. The soil water balance model SIMDualKc was used, after due calibration
and validation, using the dual crop coefficient methodology (Kc dual). A series of experiments were
done (drybeans in 2010/11; maize in secondary schedule in 2010/11; maize in 2011/12; and soybean in
2014/15), with the imposition of different irrigation deficits as treatments, using drip irrigation and
mulching. The results of SIMDualKc simulations show good agreement between the observed and
simulated available soil water (ASW) content, values of regression coefficients (b0) were in average
0,98 for drybeans, 0,97 for soybean, 1,0 for secondary schedule maize and 1,05 for regular maize. The
adjusted Kcb values for local conditions were respectively to bean, soybean and maize, 0,15; 0,15; 0,2
for the initial period (Kcb ini), 1,03; 1,0; 1,12 for the middle season (Kcb mid); and 0,2 for the end season
for all crops (Kcb end). The results of water balance for each crop show that the less water is given to the
plants, the better the water use, keeping in mind that ETc have not reduced in the same proportion.
Regarding main and secondary schedules for maize the results for soil water balance show that main
schedule maize had an increased water consumption (higher ETc) when compared to secondary
schedule. The Es component was lower than 26% of ETc, for bean and soybean, and lower than 9% of
ETc for maize, indicating the positive effect of mulching.