The effect of surface treatments on soil water storage and yield of wheat

1972 ◽  
Vol 12 (56) ◽  
pp. 299 ◽  
Author(s):  
JE Schultz

Soil water changes under six pre-seeding surface treatments and the following wheat crop were recorded at three- to four-weekly intervals in two consecutive seasons (1966-67 and 1967-68) on a hard setting red-brown earth in South Australia. The treatments were 'fallow' (initial cultivation in spring, nine months before sowing), 'grassland' (initial cultivation in autumn, two months before sowing), 'chemical fallow' (sprayed with herbicides in spring), and three fallows separately modified with gypsum, straw and hexadecanol. In both experiments grassland lost water rapidly in spring and this lower water content was never completely restored. The fallow + straw gave the biggest recharge of soil water following rain and the highest water storage efficiency during the fallow period. In 1966-67, recharge of soil water followed rain in summer at a time of high evaporation rates. The effectiveness of the treatments in increasing soil water storage was related to their ability to reduce evaporation. In 1967-68, soil water recharge occurred in autumn when evaporation rates were low. The effectiveness of the treatments was then related to their ability to curb surface sealing by raindrop impact. Nitrate-N contents in the top 60 cm of soil at seeding were higher in 1967 than 1968, probably due to efficient mineralization in 1967 after summer rain, and leaching by heavy rain and denitrification before seeding in 1968. Crops on the fallow + straw treatment used most water and produced the highest wheat yields with the highest water-use efficiency in both years.

1978 ◽  
Vol 29 (4) ◽  
pp. 653 ◽  
Author(s):  
RJ French

The effect of fallowing before a wheat crop was studied in South Australia in an environment with suboptimal rainfall in the growing season. A 9–10 month pre-sowing fallow increased mean water storage (0–120 cm depth) at sowing by 28 mm, compared with a non-fallow soil preparation (2 month period of cultivation). Variation in additional storage ranged from nil to 125 mm. These amounts depended on soil type and season: in coarse-textured soils, fallowing conserved little additional water, but in fine-textured soils much additional water could be stored. Storage was not related to the summer rainfall (November-March) before sowing but was related to rainfall during July and August in the previous winter—just before or at the start of the fallow period. A combination of these two factors, fine-textured soil and good July–August rainfall, gave considerable storage. Fallowing also increased the nitrate nitrogen content in the surface 60 cm at sowing; the mean additional nitrogen amounted to 19 kg/ha in the coarse-textured soils and 30 kg/ha in the fine-textured soils. The largest increases due to fallowing were recorded in soils following medic leys and with ample rains on the fallow in spring. Comparison is made between these findings and those obtained with fallowing in other parts of Australia.


1971 ◽  
Vol 11 (49) ◽  
pp. 236 ◽  
Author(s):  
JE Schultz

Soil water changes under fallow (initial cultivation in spring), grassland (initial cultivation in autumn) and the succeeding wheat crops were recorded at two to three weekly intervals in three consecutive seasons in three soil types representing the range of wheat-growing soils in South Australia. Differences in water content between the two treatments developed soon after the start of fallowing due to the greater loss of water from grassland in spring. Rainfall during the fallow period contributed little to soil water storage except in one year when heavy spring rains were recorded. In some instances the water content in the fallowed soils at seeding was less than at the start of fallowing, but the fallowed soils consistently retained more water than the grassland soils. Soil water contents decreased after August of the crop year (end of tillering) and by harvest the wheat crops had commonly dried the soil to a depth of 150 cm. Fallow crops used more water and produced significantly higher wheat yields with a greater efficiency of water use in all trials.


1996 ◽  
Vol 47 (3) ◽  
pp. 479 ◽  
Author(s):  
KY Chan ◽  
DP Heenan

The effects of tillage (conventional tillage v. direct drilling) and stubble management (stubble retained v. stubble burnt) on soil water storage, growth and yield of wheat were assessed over two seasons (1989-1990) in a wheat-lupin rotation on a red earth at Wagga Wagga, NSW. Soil water storage and efficiency of water use were different for the two seasons. Both direct drilling and stubble retention maintained the soil surface (0-0.1 m) at higher water content at sowing time. However, their effectiveness in increasing soil water storage at sowing was evident only in the 1990 season which, with average rainfall during the summer fallow, was drier than 1989. Average wheat grain yield was similar (4.02 v. 4.08 t/ha) for the two seasons even though the 1989 season had 245 mm more rain, the difference mainly occurring in March-April. Most of the excess water in seasons like 1989 was likely to have been lost by deep drainage, with implications for leaching of soluble nutrients, increasing subsoil acidity and rising watertables. Poor early growth of wheat when the stubble was retained and the crops direct drilled was season dependent. It was observed in the wheat crop only in the 1989 season which had a wet autumn. In that season, poor early growth which resulted in a significant yield reduction of 0.5 t/ha was associated with reduced water extraction before anthesis despite the availability of adequate soil water. No corresponding differences in growth and yield were observed for the lupin crop.


Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
Tomás de Figueiredo ◽  
Ana Caroline Royer ◽  
Felícia Fonseca ◽  
Fabiana Costa de Araújo Schütz ◽  
Zulimar Hernández

The European Space Agency Climate Change Initiative Soil Moisture (ESA CCI SM) product provides soil moisture estimates from radar satellite data with a daily temporal resolution. Despite validation exercises with ground data that have been performed since the product’s launch, SM has not yet been consistently related to soil water storage, which is a key step for its application for prediction purposes. This study aimed to analyse the relationship between soil water storage (S), which was obtained from soil water balance computations with ground meteorological data, and soil moisture, which was obtained from radar data, as affected by soil water storage capacity (Smax). As a case study, a 14-year monthly series of soil water storage, produced via soil water balance computations using ground meteorological data from northeast Portugal and Smax from 25 mm to 150 mm, were matched with the corresponding monthly averaged SM product. Linear (I) and logistic (II) regression models relating S with SM were compared. Model performance (r2 in the 0.8–0.9 range) varied non-monotonically with Smax, with it being the highest at an Smax of 50 mm. The logistic model (II) performed better than the linear model (I) in the lower range of Smax. Improvements in model performance obtained with segregation of the data series in two subsets, representing soil water recharge and depletion phases throughout the year, outlined the hysteresis in the relationship between S and SM.


2016 ◽  
Vol 13 (1) ◽  
pp. 63-75 ◽  
Author(s):  
K. Imukova ◽  
J. Ingwersen ◽  
M. Hevart ◽  
T. Streck

Abstract. The energy balance of eddy covariance (EC) flux data is typically not closed. The nature of the gap is usually not known, which hampers using EC data to parameterize and test models. In the present study we cross-checked the evapotranspiration data obtained with the EC method (ETEC) against ET rates measured with the soil water balance method (ETWB) at winter wheat stands in southwest Germany. During the growing seasons 2012 and 2013, we continuously measured, in a half-hourly resolution, latent heat (LE) and sensible (H) heat fluxes using the EC technique. Measured fluxes were adjusted with either the Bowen-ratio (BR), H or LE post-closure method. ETWB was estimated based on rainfall, seepage and soil water storage measurements. The soil water storage term was determined at sixteen locations within the footprint of an EC station, by measuring the soil water content down to a soil depth of 1.5 m. In the second year, the volumetric soil water content was additionally continuously measured in 15 min resolution in 10 cm intervals down to 90 cm depth with sixteen capacitance soil moisture sensors. During the 2012 growing season, the H post-closed LE flux data (ETEC =  3.4 ± 0.6 mm day−1) corresponded closest with the result of the WB method (3.3 ± 0.3 mm day−1). ETEC adjusted by the BR (4.1 ± 0.6 mm day−1) or LE (4.9 ± 0.9 mm day−1) post-closure method were higher than the ETWB by 24 and 48 %, respectively. In 2013, ETWB was in best agreement with ETEC adjusted with the H post-closure method during the periods with low amount of rain and seepage. During these periods the BR and LE post-closure methods overestimated ET by about 46 and 70 %, respectively. During a period with high and frequent rainfalls, ETWB was in-between ETEC adjusted by H and BR post-closure methods. We conclude that, at most observation periods on our site, LE is not a major component of the energy balance gap. Our results indicate that the energy balance gap is made up by other energy fluxes and unconsidered or biased energy storage terms.


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