MITIGAÇÃO DO DÉFICIT HÍDRICO UTILIZANDO POLIACRILATO COMO HIDRORETENTORES E ESTRATÉGIAS DE IRRIGAÇÃO: EFICIÊNCIA AGRONÔMICA, PRODUÇÃO DE BIOMASSA, SANIDADE E PRODUÇÃO DE GRÃOS E SILAGENS EM DIETAS DE RUMINANTES NO PERÍODO DE SECA

Abstract

Seasonality in forage production in Brazil is challenging for animal nutrition, meaning that during the dry period, pastures present a reduction in their growth and development, causing a low supply of forage. The objective was to determine the agronomic characteristics of the corn plant subjected to the use of moisture-retaining polymer in the soil and the qualitative and nutritional characteristics of the exclusive corn silage and in the form of feed in total mixture. The experimental design was in randomized blocks with four treatments and four replications. The treatments consisted of Control, without moisture-retaining polymer; 0 Days: moisture-retaining polymer hydrated on the day of planting; 5 Days: moisture-retaining polymer hydrated every 5 days and 10 Days: moisture-retaining polymer hydrated every 10 days. The experiment was carried out in two trials, where in trial I the following agronomic characteristics were evaluated: Whole plant weight (PPI, kg); Weight of live leaves/plant (PFV, g); Weight of dead leaves/plant (g); Production of live leaves/plant (kg/ha); Production of dead leaves/plant (PFM, kg/ha), Production of total biomass (PBT, kg/ha); Living leaf: senescent leaves ratio; Total biomass: living leaves ratio; and determine the health of the stem and leaves. In trial II, the nutritional characteristics of the silage were evaluated: Dry Matter (DM); Crude Protein (CP); Ethereal Extract (EE); Mineral Matter (MM); Fiber in Neutral Detergent (NDF); Fiber in Acid Detergent; Water Soluble Carbohydrates (CHOs); pH; Ammonia Nitrogen [(N-NH3)/Total Nitrogen]; Gas Losses (PG); Effluent Losses (PE); Dry Matter Recovery (RMS) and Aerobic Stability (EA). The feed silages in total mix were composed of 60% roughage, corn silage and 40% concentrate. They were formulated to meet the nutritional requirements of dairy cows with an average body weight of 450 kg and average milk production: 15 liters/day. There was a difference for the variable ear diameter without straw (DESP), where the use of moisture-retaining polymer in the soil showed better results. A difference (P<0.05) was observed for all corn biomass production variables due to the use of moisture-retaining polymers in the soil. For PFV, PBT, PFM and ratio of living leaves/senescent leaves, the moisture-retaining polymer hydrated every 5 days presented the highest averages. There was a difference (P<0.05) for the agronomic variables of corn grains depending on the moisture retention in the soil. There was no difference (P>0.05) for the characteristics of corn grains depending on the moisture-retaining polymers in the soil, as well as for the health of the stalk and leaves. Effluent losses showed a difference (P<0.05) depending on the moisture-retaining polymer. There was an interaction between the moisture-retaining polymer and the concentrated mixture for the ammonia nitrogen variable, there was an effect of the polymer only for the mineral matter variable, where the control treatment and 0 days presented higher averages. There was an isolated effect of the concentrated mixture for all variables. It is concluded that the use of moisture retaining polymer in soil hydrated every 5 days showed improvements in production efficiency for corn cultivation in the agricultural off-season. Meanwhile, silage in the form of feed in total mixture showed better nutritional characteristics.