MINING RESIDUE IN THE COMMERCIAL LIMESTONE BLENDING AND THE CHEMICAL ATTRIBUTES OF A LATOSOL

The limestone mining activity causes environmental impacts due to the generation of waste. However, the reuse of these residues has been investigated with the objective of improving soil fertility and acidity correction. The objective of this work was to evaluate the potential for using mining residues in the commercial limestone blending and in the chemical attributes of a dystrophic Red Yellow Latosol. The experiment was carried out in three steps: the first corresponded to the sampling and characterization of the residues in the tailings pile; the second was the combination and characterization of the new soil acidity correction agents as well as the selection of treatments based on the Neutralization Power and doses of soil acidity correction agetns (0.0; 0.5; 1.0; 2.0; 4.0 t ha-1); in the third step, a test of the incubation and calibration of the application doses of the soil acidity correction agents was performed. It was found that even with the raise in the levels of Ca2+ and Mg2+ in the correction agents, it was not possible to provide an optimal supply of nutrients to the soil, a fact explained by the low constant solubility of CaCO3 and MgCO3. However, the commercial limestone blending with tailing was efficient, as it had a significant effect on raising the pH and neutralizing the soil moisture potential.

Effect of Soil Water Potential Controlling on the Rice Growth

Pot experiments were conducted under different status of soil moisture potential during different stages of rice. The results show that soil moisture potential regulation and control is able to increase the rice yield at each growth stages after returning green, the suitable soil water potential criteria for middle-season rice in Liaoning province at different stages is 5~10kPa in tillering initial stage, 35kPa at most in tillering final stage, 5~10kPa in jointing and heading stages, not more than 20kPa in Milk maturity stage; re-watering post drought has a compensation effect to rice whose soil suction potential is controlled in 5~10kPa at tillering initial stage according to the results that its tillers number, output, final root dry biomass and leaf dry weight were significant exceeding contrast; The research on rice quality indicates that water stress in jointing stage increase protein content but reduce eating quality.

PLANT MOISTURE AVAILABILITY ASSESSMENT

The regularities of moisture behavior in the system of surface air - vegetation cover - soil with the use of moisture potential are established. It is shown that the moisture potential in soil, leaves of plants, changes in the moisture potential in the soil-plant system, and relative transpiration is related to functional dependencies. It is well established that each group plants (hygrophytes, mesophytesand xerophytes) is characterized a certain narrow range of soil moisture potential, in which the relative transpiration values do not fall below the optimal level (1.0-0.9). This interval is virtually independent of soil properties and meteorological conditions и can be used as the optimal criterion for plant moisture supply.