|Author:||Norton, R. M. ; Wachsmann, N. G.|
|Book Group Author:||NA|
The effect of management and crop selection on water use and profile drying was investigated using 2 series of experiments conducted in the Victorian Wimmera. The effect of applied nitrogen on growth and water use of canola was assessed from 3 field experiments on a Vertosol soil. Across these sites, 140 kg N/ha increased crop water use by a mean of 30 mm, and the biological response averaged 3.68 t/ha of shoot dry matter and seed yield increased by 73% from 1.46 to 2.52 t/ha. The additional nitrogen enabled roots to go deeper into the soil and also to extract water to higher tensions, but the increases in water use were far less than the growth and yield responses. Estimated average soil evaporation was 120 mm across these experiments, but ranged from 26 to 57% of total water use. It was concluded that increased crop vigour in response to applied nitrogen does increase total water use, but the main way that water-use efficiency increases is through reduced soil evaporation. In a second series of experiments, the growth, yield, and water use of wheat, canola, linseed, mustard, and safflower were compared across 4 sites with differing soil moisture contents. Wheat was the highest yielding crop at all sites. Mustard and canola produced similar amounts of biomass and seed yields, whereas linseed produced seed yields that were generally less than the brassica oilseeds. Safflower grew well and produced large amounts of biomass at all sites, but this increased growth did not necessarily translate into increased seed yields. Safflower yielded less seed than all other crops at the 2 dry sites, but yields were similar to canola at the wetter sites. On 2 drier sites, soil water extraction occurred to approximately 1 m for all crops, and all available water was used within that zone by all crops. Where the soil was wet beyond 1 m, safflower was able to extract water from deeper in the profile than the other crops and generated a soil water deficit of about 100 mm more than the other crops at maturity. This deficit persisted into the subsequent autumn-winter period. The potential of using safflower as a management option to extract water from deep in the profile, and so create a soil buffer, is discussed.
|Pages:||257 - 267|
|Journal:||Australian Journal of Agricultural Research|
application rates, crop yield, growth, nitrogen fertilizers,plant water relations, rape, roots, shoots, soil water, water use, wateruse efficiency, Australia, Brassica napus var. oleifera, Australasia,Oceania, Developed Countries, Commonwealth of Nations, OECD Countries,Brassica napus, Brassica, Brassicaceae, Capparidales, dicotyledons,angiosperms, Spermatophyta, plants, Capparales, Field Crops (FF005) (NewMarch 2000), Plant Water Relations (FF062), Plant Production (FF100),Fertilizers and other Amendments (JJ700)