Produtividade do milho sob efeito residual da aplicação de fontes de adubação fosfatada e plantas de cobertura de inverno

Abstract

Most of the soils in Brazil have the oxidic characteristic, which favors the retention of phosphorus in the soil colloids. To reduce these effects, you can increase the dose, apply it in the groove and constantly replenish the mineral for each crop, but it results in an increase in the cost of production. The objective of this work is to evaluate the residual effect of the use of phosphate fertilizers, soluble and not soluble in water, associated to the cultivation of winter cover crops in the production of plant biomass and corn productivity The experiment was implemented in 2009, the present work presents the 2018/19 harvest. The experiment contains 21 randomized block treatments in the two-factorial model (3 x 7), with three replicates. Factor A involves phosphorus sources that were triple superphosphate (44% P205 soluble in neutral ammonium citrate + water) and natural phosphate from Algeria (24% P205 soluble citric acid) and a control with absence of P, and factor B winter cover plants (PC" The sources of P were applied in the dosage of 100 kg ha-1 of P205, between the years of 2009 and 2015, from 2015 no phosphorus fertilization was carried out in order to evaluate the residual effect. The used PCI were black oat cv. IAPAR 61 (Avena strigosa Schreb), forage turnip (Raphanus sativus L.), white lupine (Lupinus albus), common ryegrass (Lolium multiflorum), hairy vetch (Vicia villosa Roth), rye (Secale cereale L.) maintained in winter fallow. These were cultivated in the months of April / May and evaluated the biomass production. In the month of September, corn sowing was carried out. The variables analyzed were corn grain yield, number of spikes per meter, number of rows per spike and number of grains per row, using a sampled area of 5.4 m2. Soil samples were taken after the management of ICP in the year 2017. The P was determined by the Anion Exchange Resin (RTA) method. In the dry matter production, there was a highlight for grasses, the largest accumulations were using the phosphate sources, with differences depending on the cover plant, so that both were superior to the control with absence of phosphorus. For maize attributes, the absence of phosphorus resulted in a reduction in all variables. The two sources used differed from one another, where the fallow, vetch, lupine, lupine and ryegrass plots with NF had higher productivity in relation to FTS. The residual effect of the two evaluated sources were statistically equivalent and capable of sustaining productivity above 10t ha-1 in maize after 3 years without phosphate fertilization in soil with a fertilization history of 100kg ha -1 of P205 per year between 2009 and 2015.