Summary
Empirical functions to predict the nitrogen uptake, increase in LAI and minimum leaf water potential (LWP) of cotton were incorporated into a water balance model for the Namoi Valley, N.S.W. A function was then developed to describe the lint yield of irrigated cotton as a function of water stress days at 4 stages of development, total nitrogen uptake and days of waterlogging. A water stress day was defined as predicted minimum leaf water potential less than -1.8 MPa up to 90 days after sowing and -2.4 MPa there-after; stress reduced yield by up to 40 kg lint ha−1 d−1 with greatest sensitivity at 81–140 days after sowing and when N uptake was highest. Nitrogen uptake was reduced by 0.98 kg per ha and yield reduced by 33.2 kg lint ha−1 for each day of waterlogging. The model was used to evaluate various irrigation strategies by simulating production of cotton from historical rainfall data. With a water supply from off farm storage, net returns ($ M1−1) were maximized by allocating 7 Ml ha−1 of crop. The optimum practice was not to irrigate until 60 days from sowing and until the deficit in the root zone reached 50%. When the supply of water was less than 7 Ml ha−1 there was no advantage in either delaying the start of irrigation or irrigating at a greater deficit; it was economically more rational to reduce the area shown or, if already sown, to irrigate part with 6 Ml ha−1 and leave the rest as a raingrown crop. Irrigation decisions are compromises between reducing the risk of water stress and increasing the risk of waterlogging. The simulation showed that there is no single set of practices that is always best in every season; in a number of seasons practices other than those which on average are best, give better results.
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Constable GA, Hearn AB (1981) Irrigation for crops in a sub-humid environment VI Effect of Irrigation and Nitrogen Fertilizer on Growth, Yield and Quality of cotton. Irrig Sci 3:17
Crowther F (1934) Studies in growth analysis of cotton under Irrigation in the Sudan. I. The effects of different combinations of nitrogen applications and water supply. Ann Bot 408:877
Cull PO, Smith RCG, McCaffery K (1981) Irrigation Scheduling of Cotton in a Climate with Uncertain Rainfall II. Development and application of a model for Irrigation Scheduling. Irrig Sci 2:141
Grimes DW, Yamada H (1982) Relation of Cotton Growth and Yield to minimum leaf Water Potential. Crop Sci 22:134
Hearn AB (1979) Water relationships in cotton. Outlook on Agriculture 10:159
Hearn AB, Constable GA (1981) Irrigation for crops in a sub-humid environment V Stressday analysis for soybeans and an economic evaluation of strategies. Irrig Sci 3:1
Hodgson AS (1982) The effects of duration, timing and chemical amelioration of short-term waterlogging during furrow irrigation of cotton in a cracking grey clay. Aust J Agric Res 33:1019
Priestly CHB, Taylor RJ (1972) On assessment of surface heat flux and evaporation using large scale parameters. Mon Wheather Rev 100: 81
Rawson HM, Turner NC, Begg JE (1978) Agronomic and physiological responses of soybeans to water deficits IV. Photosynthesis, transpiration and water use efficiency of leaves. Aust J Plant Physiol 5:195
Ritchie JT (1972) Model for predicting evaporation from a row crop with incomplete cover. Water Resour Res 8:1204
Turner NC, Begg JE, Rawson HM, English SD, Hearn AB (1978) Agronomic and physiological responses of soybean and sorghum crops to water deficits III Components of leaf water potential leaf conductance, 14CO2 photosynthesis, and adaption to water deficits. Aust J Plant Physiol 5:179
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Hearn, A.B., Constable, G.A. Irrigation for crops in a sub-humid environment VII. Evaluation of irrigation strategies for cotton. Irrig Sci 5, 75–94 (1984). https://doi.org/10.1007/BF00272547
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DOI: https://doi.org/10.1007/BF00272547