The Influence of Period of Sowing of Winter Fodder Pea Variety on Tuber-Formation and Plant Residues Content for Improving Soil Fertility

Abstract

The study of plant-microbial associations is important for the developmentof modern farming and environment ecology. In the process of thegradual reduction of import quantities of mineral fertilizers and pesticides toincrease the plants productivity and yield it is necessary to activate the agrocenosesbiological components, where learning about the legume bean-rizobialsymbiosis is very important. Increasing the reserves of symbiotic nitrogenfixation, mobilization and provision of the plants with environmentally safebiological nitrogen and its storage in the soil are the reasons for constant researchesand experiments.The purpose of this study is to determine the infl uence of the period ofsowing on the development of the root mass, tuber-formation, the amountof post-harvest residues and soil agrochemical composition of winter fodderpeas. The experiment is made in the period of 2005 to 2008 in Pleven EFC withthe method of random block system. The results show that in the fi rst samplingmaximum number of tubers (26.62 g plant) and root dry weight (1.55 g/plant)were formed in a second sowing period (10-15 October), but with the greatestamount of post-harvest residues (435.5 kg/ha) are those of the a third period(25-30 October). After the harvest and the secondary growing of peas the indicatorsvalue are lower by 76.2, 30.2 and 61.6%.The agrochemical soil analysis shows pronounced trends in mineral nitrogenand organic carbon content under the infl uence of different sowingperiods. The soils where the plants are harvested from later sowing time are characterized with high nitrogen and carbon content determined by the largerroot volume and post-harvest residues in these terms. After the pea harvest thecurrent and potential soil acidity values decreased by 2.7 and 5.5 percent comparedwith the control variant.