WATER EROSION UNDER THREE TILLAGE METHODS IN A CULTIVATION OF Eucalyptus benthamii

Abstract

-Soil tillage influences the development of forests planted in the initial phase, which affects some hydrological processes and water erosion. The objective of this study was to quantify the water losses (WL) and soil losses (SL) by water erosion, between the second and third years of eucalyptus (Eucalyptus benthamii) crop, in an experiment located in southern Brazil, on a Humic Dystrudept. Was study three soil tillage treatments: i) subsoiling in downslope direction (SD); ii) subsoiling in contour on the slope (SC); iii) manual holes (MH). The plots had a dimension of 12 x 24 m, being the slope-wise length the greatest, monitored by tanks placed at the lower end for runoff collection. Runoff volume measurement and sampling for subsequent calculation of WL and SL was carried out weekly, corresponding to the rains accumulated during the week. The crop of eucalyptus in SD treatment, weakened the soil as to the water erosion in relation to the crop made in SC and in MH; the difference was 25% for the WL and 53% for the SL. Eucalyptus reforestation played an important role in the control of water erosion, regardless of the type of soil tillage. The SL due to water erosion were more influenced than the WL, regardless of the type of soil crop used. WL and SL are related to each other and to rainfall height in positive linear relationship, regardless of the type of soil preparation used for eucalyptus planting.Keywords: Reforestation; Water loss; Soil conservation. EROSÃO HÍDRICA EM TRÊS MÉTODOS DE PREPARO DO SOLO NUM CULTIVO DE EUCALYPTUS BENTHAMIIRESUMO -O preparo mecânico do solo é uma das operações mais importantes de manejo na fase inicial de desenvolvimento das florestas plantadas, pois afeta alguns processos do ciclo hidrológico e a erosão hídrica, sendo, por isso, importante o conhecimento dessas variáveis. Com o presente trabalho objetivouse quantificar as perdas de água e solo por erosão hídrica pluvial, entre o segundo e o terceiro ano de cultivo do Eucalyptus benthamii, em um experimento situado no Sul do Brasil, sobre um Cambissolo Húmico alumínico léptico, em três tratamentos de preparo do solo: i) preparo com subsolagem a favor do declive; ii) preparo com subsolagem em contorno ao declive; iii) preparo em covas com coveador manual. As parcelas tinham dimensão de 12 x 24 m, com o maior comprimento no sentido do declive, monitoradas por tanques colocados ao seu final para coleta da enxurrada. A medição do volume e a coleta de amostras da enxurrada para posterior cálculo de perdas de água e solo foi realizada semanalmente, correspondendo às chuvas acumuladas na semana. O preparo do solo a favor do declive apresentou perdas de água e solo maiores do que em contorno e em covas, cuja diferença foi 25 % para as perdas de água e 53 % para as perdas de solo. O crescimento das plantas ocasionou sensível diminuição do escoamento superficial, evidenciando que o reflorestamento, nas condições experimentais, pode controlar a erosão hídrica. As perdas de solo por erosão hídrica foram influenciadas em magnitude...

Water Erosion in Eucalyptus Forest in the Municipality of Otacílio Costa (Sc)

“…This justifi es the adoption of supportive conservation practices to hold these losses, storing runoff water within the cultivation area. In percentage terms, the total annual WLs showed very low values compared to the height of the rains, varying between 0.020% and 0.058%, therefore, substantially lower than the WLs verifi ed by Magro et al (2011) and Padilha et al (2017). Magro et al (2011) and Padilha et al (2017) found SL values of up to 19,700 kg ha -1 and 520 kg ha -1 , respectively.…”

“…In percentage terms, the total annual WLs showed very low values compared to the height of the rains, varying between 0.020% and 0.058%, therefore, substantially lower than the WLs verifi ed by Magro et al (2011) and Padilha et al (2017). Magro et al (2011) and Padilha et al (2017) found SL values of up to 19,700 kg ha -1 and 520 kg ha -1 , respectively. The low SL values verifi ed in this research are due to the same factors that contributed to the low WL, that is, the canopy of the plants, the vegetal mass in the form of litter and the galleries in the soil opened by the roots.…”

“…The lower WL in the SMP is explained by the smaller area of soil turned in this treatment, when compared with mechanized management (MPD and MPC). Magro et al (2011) obtained WL values varying from 4 to 14% of the rainfall volume, while Padilha et al (2017) obtained values varying from 2 to 3%, in the same treatments. Although WL may seem low, still they cannot be disregarded, considering the importance of water in the soil for the life cycle of soil plants and organisms.…”

“…CV: coefi ciente de variação. and Padilha et al (2017) is due to the growth of the forest that occurred during the research, increasing the litter biomass on the soil, the canopy of the treetops and the roots of the plants. The behavior of decreasing surface runoff over time in forest areas is also confi rmed when comparing the values of this research with those obtained by Pires et al (2006); Baptista and Levien (2010); Padilha et al (2017) and Sun et al (2018).…”

Water Related Ecosystem Services in Brazilian savannas, in landscapes of natural vegetation and eucalyptus plantations

“…Several studies have tried to identify and measure gains or losses in water services to get realistic sceneries with high-quality data (KEELER et al, 2012;OJEA, MARTIN-ORTEGA, 2015, LA NOTTE et al, 2015ZHENG et.al, 2016;DING et al, 2016), many present monetary valuation techniques aiming at better policy choices (DI SABATINO et al, 2013;OJEA, MARTIN-ORTEGA, 2015, LA NOTTE et al, 2015.…”