Efeitos de diferentes níveis de gesso e matéria orgânica na recuperação de solo com problema de sódio.

Abstract

The objectives of this work were to evaluate the effects of different levels of gypsum and organic matter, isolated and intercropped in soil recovery with sodicity problems, as well as their subsequent effects on the growth, development and production of rice (Dryza sativa, L.). The work was developed under greenhouse conditions from October 1988 to March 1989, using a sodium soil from the Irrigated Perimeter of São Gonçalo (sector 10), Sousa-Pb, and the cultivar BR rice -IRGA-409. The experimental design was a completely randomized design with 3 replicates and 6 different combinations of gypsum and corral manure (EC), namely: T1 - Witness (without correction), T2 - 29.4 t / ha of EC equivalent to 1% of soil weight at 20cm depth, T3- 23t / ha equivalent to gypsum (NG) requirement to completely replace exchangeable sodium, T4-75% NG + 25% EC used in T2, T5 - 50% NG + 50% EC used in T2 and T6 - 25% NG + 75% EC used in T2. The correctives were incorporated in the first 10 cm of soil and during the period of 50 days, to carry out the washing of the soil, a blade of constant water of 5 cm was maintained. Then the rice seedlings were planted, leaving only 3 plants per pot at 15 dais. Thereafter, the 5 cm constant water blade was maintained in all treatments. in treatments where at least 50% NG (T3, T4, T5) was incorporated, there was a sodium leaching approximately 2 times higher than the treatments T2 and T6, whereas for the control the leaching began at the end of the period. Another important aspect to note is that these first treatments also had a relatively high sodium leaching rate, since about 70% of the exsiting sodium in the soil had been leached within 20 days of the start of recovery. The PST values ​​described in all treatments, being the treatment that received 100% NG, which presented higher efficiency. It is observed that the following order of lowering of the PST was higher in the treatments that received higher amount of gypsum. However, these differences were not marked among the treatments that received NG equivalent to 50, 75 and 100% respectively. The results obtained highlight the positive effect of the gypsum / manure interaction in the recovery of soil with sodium problem. In general, the treatments studied, except for the control, showed beneficial effects on the growth, development and production of rice. The results showed significant differences between treatments at the 1% probability level in the number of tillers and panicles, in the production, aerial and root weight and in the average weight of 100 grains. In the production, treatments presented the following decreasing sequence: T5 - (38.0g), T4 - (36.0g), T3 - (29.9g), T6 - (22.4g), T2 - (21.7g) and T1 - (2, 1g). Soil analyzes, after harvesting the rice, showed that the crop also promoted a reduction of soil PST in all treatments.