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| Titel |
Water erosion during a 17-year period under two crop rotations in four soil management systems on a Southbrazilian Inceptisol |
| VerfasserIn |
Ildegardis Bertol, Eva Vidal Vazquez, Jorge Paz Ferreiro |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043030
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| Zusammenfassung |
| Soil erosion still remains a persistent issue in the world, and this in spite of the efforts to
ameliorate soil management systems taken into account the point of view of environmental
protection against soil losses. In South Brazil water erosion is mainly associated to rainfall
events with a great volume and high intensity, which are more or less evenly distributed all
over the year. Nowadays, direct drilling is the most widely soil management system used for
the main crops of the region. However, some crops still are grown on conventionally tilled
soils, which means mainly ploughing and harrowing and less frequently chisel ploughing.
In Lages-Santa Catarina State, Brazil, a plot experiment under natural rain was
started in 1992 on an Inceptisol with the aim of quantifying soil and water losses.
Treatments included bare and vegetated plots. The crop succession was: oats (Avena
strigosa), soybean (Glycine max), vetch (Vicia sativa), maize (Zea mays), fodder
radish (Raphanus sativus) and beans (Phaseolus vulgaris). Soil tillage systems
investigated in this study were: i) conventional tillage (CT), ii) reduced tillage (MT), iii)
no tillage (NT) under crop rotation and iv) conventional tillage on bare soil (BS).
Treatments CT and BS involved ploughing plus twice harrowing, whereas MT
involved chisel ploughing plus harrowing. Rainfall erosivity from January 1 1992 to
December 31 2009 was calculated. Soil losses from the BS treatment along the 17 year
study period were higher than 1200 Mg ha-1. Crop cover significantly reduced
erosion, so that under some crops soil losses in the CT treatment were 80% lower
than in the BS treatment. In turn soil losses in the MT treatment, where tillage was
performed by chiselling and harrowing, were on average about 50% lower than
in the CT treatment. No tillage was the most efficient soil management system
in reducing soil erosion, so that soil losses in the NT treatment were about 98%
lower than in the BS treatment. The three vegetated treatments, CT, MT and NT
showed a lower efficiency in reducing water losses than soil losses. Water losses by
runoff during a number of events were of the same order of magnitude for all the
management systems studied here; which was mainly true when the volume of
rainfall was high and the lag between successive events was small. In general, soil
losses in the autumn-winter seasons were lower than under the spring-summer
seasons. Soil losses showed a positive correlation with rainfall erosivity. However, the
degree of dependence between these two variables decreased as the efficiency of
soil management in controlling soil erosion increased. The large soil and water
losses in the BS and CT treatments suggest that there is a need to implement soil
conservation measures in the study region. In this context soil conservation would
take advantage from soil cover by previous crop residue as well as from terrace
building.
Acknowledgement: This work was partly supported by Spanish Ministry of Education
(Project CGL2005-08219-C02). |
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