The control of drip irrigation of sugarcane using “index” tensiometers: Some comparisons with control by the water budget method

• Published in: Agricultural water management 1990, Vol.17 (1), p.189-207
• Main Authors: Hodnett, M.G., Bell, J.P., Ah Koon, P.D., Soopramanien, G.C., Batchelor, C.H.
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agronomy. Soil science and plant productions; Biological and medical sciences; CALENDARIO DE LOS RIEGOS; CALENDRIER DES IRRIGATIONS; CANA DE AZUCAR; CANNE A SUCRE; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; IRRIGATION GOUTTE A GOUTTE; IRRIGATION SCHEDULING; POTENCIAL HIDRICO DEL SUELO; POTENTIEL HYDRIQUE DU SOL; RIEGO POR GOTEO; SOIL WATER POTENTIAL; SUGAR CANE; TRICKLE IRRIGATION; Water balance and requirements. Evapotranspiration
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/0378-3774(90)90065-7

A method is described for scheduling the drip irrigation of sugar cane using ‘index’ tensiometers. Water is applied to maintain a chosen point in the profile near the dripline and root zone at a constant soil moisture potential. The quantities of water to apply each day are determined from the tensiometer readings using simple guidelines. The method does not require estimates of crop evaporation or measurements of rainfall. A field trial was run to compare the index method of control with irrigation control based on water budgetting using estimates of crop evaporation derived from potential evaporation values. With the latter method of control, treatments were given their full water requirement (1.0 ETc) or half their water requirement (0.5 ETc), when irrigation was necessary. The amount of water applied to the index treatments lay between that applied to treatments given 1.0 ETc and that given to treatments receiving 0.5 ETc. Compared to the treatments receiving 1.0 ETc, the main saving of water by index control was made in the tillering phase. Overall, yields obtained using index control were slightly better than with water budget control. The best yields were obtained with index control, but in the crop season concerned, which had above average, and well distributed rainfall, good yields were obtained from the 0.5 ETc treatments. These had the highest water use efficiency. There seems to be scope for modifying the index method to make greater use of water stored in the profile after rainfall, to improve the water use efficiency. This applies particularly to the boom phase of cane growth, which in Mauritius, coincides with the wettest time of the year.