Recomendação de calagem para alguns solos do Estado do Amazonas

Abstract

Upland soils Amazonas state is characterized by having pH and Al3+ at levels that limit the good yields. The objective of this study was to evaluate the chemical changes in function in soils of the addition of different levels of limestone and estimate quantities needed corrective to reach pH arable. We used a completely randomized block design with three replications. The treatments consisted of a factorial 3 x 7 by matching three textural classes (medium texture, clay, and much clay) with seven levels of limestone (0, 1.0, 2.0, 4.0, 6.0, 8, 0 to 10 t ha-1). After 56 days of incubation, the pH values were determined in water; this was plotted versus liming and adjusted polynomial regression models, to determine the quantity of lime necessary to achieve pH 5.5; 6.0 and 6.5. At that time, it was determined the Al3+ content, Ca2+, Mg2+, K and H + Al and from these values calculated the base saturation (V%). The efficiency of liming by incubation curve method was evaluated in experiments conducted in a greenhouse through the effect of different rates of lime in the production of MSPA and MSR in the corn and bean crops. The treatments were arranged in a completely randomized design in a factorial 2 x 7, combining two soil (Ultisol and Oxisol) and seven levels of limestone (0, 1.0, 2.0, 4.0, 6.0, 8.0 and 10 t ha-1), with four replications. The data MSPA, MSR and content of P, K, Ca, Mg, Zn, Fe, Mn and Cu in the shoots were adjusted regression models and then estimated the limestone, corresponding to the ESM. The soil showed high significance indices with the amount of lime to raise the pH of the soil, and the levels of 0.3; 2.2 and 4.0; 2.6; 4.4 and 6.1; 2.2; 4.0 and 5.8 t ha-1 of lime in medium textured soils, clayey and much clayey are recommended to achieve the pH 5.5; 6.0 and 6.5, respectively. The recommendation of 1.5; 2.6 to 2.2 t ha-1 was sufficient to reduce Al3+ and the doses of 3.7; 4.7 and 4.6 t ha- 1 increasing the saturation to levels appropriate for crop development, corresponding to water pH around 6.3; 6.0 and 6.5 in medium textured soils, clayey and much clayey, respectively. The quantities of limestone corresponding to maximum economic yield MSPA and MSR both corn as the beans are close to the amount recommended by the method of incubation curve required to achieve the pH acceptable for cultivation and these doses have not reduced below the deficiency of the content absorption during the first 60 days of cultivation.