The effects of strip cropping system, grass buffers strips and slope position on some physico-chemical properties at cambic chernozem from Iaşi county

Abstract

The research was carried out on the sloping land from the Agricultural Research Station of Podu- Iloaiei, Iasi (47°12´ N latitude, 27°16´ E longitude) and the Experimental Farm of the University of Agricultural Sciences and Veterinary Medicine, Ezareni (47°07´ N latitude, 27°30´ E longitude) on a cambic chernozem (SRTS-2003). The parameters analyzed were soil texture, bulk density, aggregate stability (physical characteristics) as well as soil pH, SOM, basic cations (Ca, Mg, K), N and P (chemical characteristics). The climatic conditions in the Moldavian Plain were characterized by annual mean temperature of 9.6oC and a mean rainfall amount, on 50 years, of 553.5 mm, of which 141.5 mm during September-December and 412.0 mm during January-August. At the beginning of the sampling, the study of the researched area was carried out and the GPS was used to identify the geographic location and the coordinate system in the researched areas. Data on soil properties were recorded on thematic maps, scale 1: 2000 and processed using the AutoCAD software. The results obtained on soil erosion indicate that from the total amount of precipitation recorded – 549.8 mm, 338.5 mm (61.6%) generated leaks that varied between 8.2 mm at perennial grasses in the second year of vegetation and 33.4- 35.9 mm at maize and sun flower crops. The annual soil losses due to erosion raged between 0.193 t/ha at perennial grasses in the second year of vegetation and 7.657-8.328 t/ha at maize and sunflower. The percent of hydrostable aggregates ranged between 65.5% at non-eroded soil from the base of the slope and 35.7 at highly eroded soil. Soil erosion caused a reduction in the percentage of aggregate by 14.5% to slightly eroded soil and 37.7% in the strongly eroded soil. The percentage of water stable aggregates was comprised between 73.5% in non-eroded soil, at the bottom of slope land and 45.7% at the highly eroded soil. Erosion influences soil fertility by removing along with the eroded soil, high amounts of mineral elements: 15.02 – 16.36 kg/ha nitrogen, 1.05 – 1.2 kg/ha phosphorus and 1.84 – 2.08 kg/ha potassium, in maize and sunflower crops. The crop structure, which determined the diminution in mean soil losses by erosion until 2.2 t/ha included 20 % straw cereals, 20% annual legumes, 20% row crops and 40 % perennial grasses and legumes. On land with a slope of 16%, lowering the percentage of weeding plants from 60% to 20% has reduced the amount of eroded soil by 47.1% (1.966 t/ha/y). At Ezareni, on the land with a 12% overall slope, given the agro-terraced process that appeared in time due to soil erosion and tillage, the slope of cultivated stripes decreased, depending on the slope of the land, to 7.40-10.78% and the slope of the taluses increased from 12.78 to 26.18%. At Podu-Iloaiei, on the land with a general slope of 13%, through the agro-terracing process, the slop