Soil preparation and nutrient losses by erosion in the culture cucumber

Abstract

Minimum tillage reportedly reduce erosion, avoid soil degradation and improve crop productivity. This study aimed to determine how tillage operations may affect either nutrient accumulation or nutrient losses by erosion. The study was, carried out from December, 2000 to March, 2001, in the watershed of the Caetés River, in Rio de Janeiro State, Brazil (22º25'43"S, 43º25'07"W). The experiment was set up in sandy clay Kandiudult soil, 60% slope, under cucumber (Cucumis sativus L.) crop. Soil samples were collected before planting and after harvest, on 22.0 X 4.0 m Greeoff plots. After each rainfall, fine sediments carried by runoff were deposited into two collecting tanks in a row, installed at the end of each plot, and were later dried, weighed and stored for analyses. Treatments (n = 4) were characterized by different tillage systems: (i) downhill plowing followed by the burning of crop residues (DPB); (ii) downhill plowing with no burning of the crop residues (DPNB); (iii) animal traction contour plowing, with strips of guinea grass planted at a spacing of 7.0 m (AT); and (iv) minimum tillage (MT). Samples of the soil-plowed layer were collected before planting and after harvest, between the rows and from the plants. Total concentration of Ca, Mg, K and P were determined after extraction with nitric perchloride digestion. Labile P and exchangeable K were extracted with the Mehlich 1 extractant solution. The MT system reduced losses of both exchangeable bases (15%) and P (8%), and affected the distribution of labile and organic P. Crop residues left on soil surface in the MT system, resulted in increased organic matter content. Downhill plowing, the most used tillage operation in the region, resulted in the greatest losses of Ca, Mg, K, and P.

Valuation and assessment of soil erosion costs

“…Bennett (1929Bennett ( , 1933Bennett ( , 1935Bennett ( , 1939Bennett ( , 1940Bennett ( , 1955, Pimentel et al (1995) and Uri (2000Uri ( , 2001 are among the leading researchers who have devoted time and effort to study the costs of on-site soil erosion (based on nutrient losses and drops in yield) and off-site soil erosion (based on off-site impacts). On-site costs can be calculated using the cost of nutrient replacement, associating the physical quantity of erosion associated with nutrient losses, normally macronutrients: calcium, phosphorus, magnesium, nitrogen and potassium (Amaral Sobrinho and Mazur, 2005;Adhikari and Nardella, 2011;Bertol et al, 2005Bertol et al, , 2007Gunatilake and Vieth, 2000;Marques et al, 1961;Pimentel et al, 1995;Pugliesi et al, 2011;Tengberg et al, 1997) calculated on the basis of market prices for commercial fertilizers and the quantity necessary to replace lost nutrients, plus the application cost. The calculations can be based on lost yield, i.e.…”