Erosión y desertificación.-The impact of the cropping system management on soil erosion and fertility in Northeastern Romania

Abstract

ABSTRACT The influence of different crop structures, rotations and fertilizers on crop yield and soil fertility has investigated at the Agricultural Research and Development Station of Podu-Iloaiei since 1968. These experiments were carried out on a 14 % slope field, on a Cambic Chernozem with clayey loam texture (423 g clay, 315 g loam and 262 g sand), a neuter to weakly acid reaction and a mean nutrient supply. The mean annual rainfall amounts, registered in the last 28 years, were higher, with values comprised between 12.7 and 279.2 mm, compared to the multiannual mean on 80 years (544 mm) in 18 years, and lower by 25.3 - 236.7 mm in 10 years. Placing winter wheat in 3 and 4- year crop rotations with annual and perennial legumes has resulted in getting yield increases of 23 - 26 % (646 - 736 kg·ha-1), against continuous cropping. The average yield increases in wheat, during 1981-2008, were between 23 and 26 % (646 - 736 kg·ha-1), due to crop rotation, and between 57 and 101 % (1099 - 1949 kg·ha-1), due to applied fertilizer rates. The mass of total carbon from Cambic Chernozem in the Moldavian Plain has recorded significant increases at higher than N140P100 rates, in organo-mineral fertilization and in 4-year crop rotation, which included melioration plants of perennial grasses and legumes. In maize continuous cropping and wheat-maize rotation, very significant values of the carbon content were found only in the organo-mineral fertilization, in 4-year crop rotations + reserve field cultivated with perennial legumes and under N140P100 fertilization. In comparison with 4-year crop rotations, in wheat-maize rotation with melioration plants (annual and perennial legumes and perennial grasses), the mean carbon content from soil has diminished from 18.6 to 16.4 C, g·kg-1 and the content in mobile phosphorus decreased from 51.6 to 36.8 P-AL, mg·kg-1. The 40 year use of 3 and 4- year crop rotations has determined the increase in total carbon mass and mobile phosphorus from soil by 10% (1.7 C g·kg-1) and 31%, respectively (11.8 PAL mg·kg-1), against maize continuous cropping.