Constante Termica

J. Agronomy & Crop Science (2012) ISSN 0931-2250

MISCELLANEOUS

Estimation of Soil Evaporation During Fallow Seasons to
Assess Water Balances for No-Tillage Crop Rotations
L. R. Salado-Navarro1, T. R. Sinclair2 & M. Morandini3
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1 Facultad de Agronomıa y Zootecnia, Universidad Nac. de Tucuman, Tucuman, Argentina
2 Department of Agronomy, University of Florida, Gainesville, FL, USA´
3 Estacion Experimental Agropecuaria Obispo Colombres, Tucuman, Argentina

Keywords
maize; no-tillage; soil evaporation; soil water;
soybean
Correspondence
T. R. Sinclair
Department of Agronomy, University of
Florida, PO Box 110965, Gainesville, FL
32611-0965, USA
Tel.: +1 352 392 6180
Fax: +1 352 392 6139
Email: trsincl@ifas.ufl.edu
Accepted April 20, 2012doi:10.1111/j.1439-037X.2012.00520.x

Abstract
Estimates of soil evaporation and available soil water of no-tillage fields under
farm conditions are important to assess soil water status at sowing of rainfed
grain crops. The objective of this study was to predict stored soil water of notillage fields during the fallow periods following soybean (Glycine max (L.)
Merr.) and maize (Zea mays L.) crops by accounting fordecreased soil evaporation as a result of the residues left on the soil surface. Three simple phenomenological models were used to simulate stored soil water under field
conditions at seven locations in Argentina. Two models calculated decreased
soil evaporation based on crop residue mass, and the third assumed a constant
fractional decrease in bare soil evaporation. All models gave goodestimates of
soil water content during the fallow periods following a soybean crop. In cases
with large quantities of maize residue, however, the models resulted in more
water retention in the soil than observed as a consequence of underprediction
of soil evaporation. These results indicate that full benefit of crop residue was
not being achieved in these fields, probably due to a failure to finelychop and
uniformly distribute the crop material on the soil surface.

Introduction
Rainfall amount commonly limits the yield of rainfed
crops because water is needed to support plant transpiration. One approach to increase the amount of water
available for crop transpiration is to use no-tillage management practices that leave residue from the previous
crop on the soil surface to decreasesoil evaporation (e.g.
Zaman and Mallick 1991). In Argentina, nearly all grain
productions are now based on continuous no-tillage management in rotation schemes of soybean (Glycine max
(L.) Merr.), wheat (Triticum aestivum L.) and maize (Zea
mays L.). More than two-thirds of the area is currently in
only one crop per year (mostly soybean and some maize),
under the no-tillage system. For thisreason, Caviglia and
Novelli (2011) suggested that an intensification of the
cropping system is needed to increase grain production
and usage of the rainfall (800–1000 mm year)1). Based
on the data obtained from farms using no-tillage manage-

ª 2012 Blackwell Verlag GmbH

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ment in the Santa Fe Province over 10 years, Martınez
(2011) estimated the grain yield, water use efficiency and
Cbalance for a Pampas region with 1000 mm year)1 of
rainfall (Table 1).
The retention of crop residue on the soil surface has
the potential to decrease soil evaporation, particularly
during the fallow months between crops and the early
weeks of crop establishment. There are no published estimations of the soil evaporation for no-tillage conditions
in Argentina, even though its lower levelcompared to
conventionally tilled fields is implied owing to the higher
crop yields obtained (Caviglia and Novelli 2011, Fabrizzi
´
et al. 2005, Martınez 2011). Fabrizzi et al. (2005) studied
the soil water dynamics and the soil physical properties
under minimum and no-tillage on the Pampas area of
Argentina. They concluded that under no-tillage, higher
yields were observed owing to the...