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| Titel |
Water Erosion in Relation with Soil Management System and Crop Sequence during 20 Years on an Inceptisol in South Brazil |
| VerfasserIn |
I. Bertol, J. Schick, F. T. Barbosa, J. Paz-Ferreiro, M. T. Flores, A. Paz González |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061388
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| Zusammenfassung |
| Soil erosion still remains persistent at the world scale, even if big efforts have been done to
control and reduce it, mainly using soil crop residues to protect soil surface. Although in
South Brazil the main management system for most crops is no tillage and direct drilling,
water erosion prevails as the most important soil erosion type, which is due both, to the high
erosivity and the evenly distribution of rainfall over the year. Moreover, some crops are still
grown under soil tillage systems consisting of ploughing, harrowing and less frequently
chiselling. Starting 1992, a field experiment under natural rainfall has been conducted on an
Inceptisol located in Lages, Santa Catarina State, Brazil, which objective was to assess
rainfall water erosion. Two soil cover conditions and four soil management systems were
studied: I) a crop rotation, which included oats (Avena strigosa), soybean (Glycine
max), common vetch (Vicia sativa), maize (Zea mays), fodder radish (Raphanus
sativus) and common bean (Phaseolus vulgaris) under the following soil management
types: 1) ploughing plus two levelling operations (CT), chiselling plus levelling (RT)
and direct drilling with no tillage (NT), and II) bare soil (BS) without crop cover
tilled by ploughing plus two levelling. In more than 90% of the study cases, soil
losses were collected for single rain events with erosive power, whose erosivity
was calculated. Total rain recorded during the 20 year experimental period was
approximately 66,400 mm, which is equivalent to roughly 105,700, MJ mm ha-1
h-1 (EI30), whereas soil losses in the BS treatment were higher than 1,700 t.ha-1.
On average, soil losses under RT treatment showed a 92% reduction in relation
with BS, whereas under CT the reduction in relation to BS was about 66%. Soil
management by direct drilling (NT) was the most efficient system to minimize water
erosion, as soil losses decreased about 98% when compared with BS. Moreover, soil
management systems with a crop rotation, i.e., RT, CT, and NT, showed a lower
efficiency in the reduction of water losses with regard to the efficiency of soil losses
decrease. So many rainfall events during our experimental period showed similar
water losses for all the management and crop systems, which was mainly true for
rainfalls causing high volumes of runoff and with a small time interval between
successive events. During the autumn-winter seasons water losses were lower than in the
spring-summer seasons, whereas greater soil losses in the spring-summer season
were solely recorded in the CT and BS treatments. Heavy water losses by runoff
recorder under conservation tillage, specifically in the NT management system suggest
the need for adoption of additional structural conservation practices, such as for
example terracing, in order to supplement the positive effect of soil cover by crop
residues in controlling water erosion. Soil losses showed a positive correlation
with rainfall erosivity and the significance of this relationship decreased as the
efficiency of soil management system for the control of soil erosion increased. |
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