EDAFOLOGÍA, VOL 13. (1), PP 57-68 2006
CONSEQUÊNCIA DO SISTEMA DE PREPARO DO SOLO NO ACÚ- MULO E PERDA DE FÓSFORO E BASES TROCÁVEIS POR EROSÃO
J.E.V. NÚÑEZ(1), N.M.B. AMARAL SOBRINHO(2)(3); N. MAZUR(2)(4)
1Instituto de Investigación Agropecuaria de Panamá (IDIAP). Apartado 58,
Santiago, Província de Veraguas.Panamá 2Departamento de Solos da Universidade
Federal Rural do Rio de Janeiro (UFRRJ). CEP 23890 000 Seropédica (RJ), Brasil
3 Bolsista do CNPq 4 Autor correspondenteDepartamento de Biología Vegetal, Facultad de Farmacia, Universitat de Valéncia,
Av. Vicent Andrés Estellés s/n, 46100 Burjassot (Valencia), Spain. boluda@uv.es
This study aimed to determine the influence of different methods of tillage on the accu- mulation and loss of nutrients by erosion. The experiment was conducted in the Caetés watershed, city of Paty do Alferes RJ, during the months from January to March 1997 in the crop cycle of cucumber (Cucu- mis sativus L.). The experiment was located Red Yellow, intermediate texture latossólico sandy clay / clay and slope of 60%. Were installed Wischmeier-type plots in an area of 22.0 x 4.0 m getting different tillage systems of soil. At the end of each plot were installed two tanks for the storage of rainwater and sediment carried by runoff. The treatments used were: (i) with tractor plowing down hill and burning of crop residues (MAQ), (ii)with tractor plowing down hill with no burnt remains of natural vegetation between the lines (MANQ), (iii)tillage with animal traction in level, grass tracks, each placed 7.0 m (AA) and (iv) minimum tillage, roçado and coveamento (CM). Is used four replicates per treatment. On lines and mounds of each plot was collected samples of the arable layer of soil before planting and after harvest. After each rain the sediment carried by erosion were collected, dried, weighed and saved for later analysis. Samples of soil and sediment were destorroadas, passed through a sieve of 2 mm, ground in agate mortar and passed by the sieve of 500μm. The total concentration of Ca, Mg, K and P were determined in extracts obtained from the digestion nitro perchloric. OP labile and exchangeable K were extracted with the solution of extractor Meh- lich 1 (North Carolina). The exchangeable Ca and Mg were extracted with solution of KCl 1N. P was frac- tionated into organic and inorganic forms through the method of Bowman. The carbon was determined using the Walkley Black wet digestion, and pH determined in water in proportion 1:2.5 (soil water). The CM re- duced the loss of exchangeable bases and P and also influence the distribution in the labile and organic forms of P. The use of vegetable waste in the plot under CM, an increase in organic matter content. Treat- ment MAQ, typical of the region, was the most loss of Ca, Mg, K and P.
Key words: soil cultivation, P fraction, soil erosion loss.