The value of sugar was calculated assuming a contract price of £22.50 per adjusted tonne less levy contributions and extra harvest costs giving a value to the grower of £118/ t sugar. It was assumed that irrigation would be carried out using a hose-reel fitted with a rain-gun and applying 25 mm at each irrigation. The cost of each application is £53/ha, comprising labour, tractor hire, water and diesel for pumping. It was assumed that an irrigation system was already in place and normally used for other crops, therefore capital costs were not included in the analysis.
Taking a loamy sand soil at Bury St Edmunds as an example, the average net benefit of irrigating was -£25/ha (i.e., on average the additional sugar yield did not cover the additional cost of applying water) however, it ranged from £69/ha in the driest 10% of years to -£124/ha in the wettest 10% of years
Irrigation in June or July both produced larger increases in sugar yield and produced a positive net benefit in average or drier years. Irrigation in August or September generally did not cover the cost of irrigating.
- To quantify the response of sugar beet to irrigation and the economics of irrigating sugar beet through an extensive literature (science and grey) review;
- To define future plausible agroclimatic scenarios based on historical data analysis;
- To assess sugar beet irrigation needs and yield response to irrigation based on biophysical crop modelling techniques using grower information and historical climatic data;
- To estimate the financial net benefits of irrigation.
Outcomes / Key Message For Growers And Industry
- Sugar yields show a modest increase under irrigation in most years and on most soil types in the beet growing areas of England, but the largest increases occur in dry summers and on the lightest soils.
- If irrigation equipment is already available on the farm, the cost of applying one 25 mm irrigation with a hose-reel irrigator and rain-gun is typically £53/ha comprising labour, tractor use, water cost and diesel for pumping. At current sugar prices (£22.50 per adjusted tonne of beet), this would require an increase of 0.45 t sugar/ha to justify the cost of irrigating.
- The net benefit of irrigating depends on the weather. In a all but a “very dry” summer (expected, on average once in five years) the increase in sugar yield would not be sufficient to cover the cost of irrigating.
- Irrigating in June and July shows the greatest benefit and generates a net benefit in average or drier summers, especially on lighter soils. However, this is the time of year when other crops on the farm are also demanding irrigation water and decisions about which crop to prioritise will depend on which shows a greater financial response.
- Irrigating sugar beet in August or September, in general, does not result in sufficient sugar yield increase to offset the cost of irrigating.
- At the current contract price for sugar beet, the financial benefit of irrigation is marginal in all but the driest summers, however, a higher beet price (such as in 2014) would justify irrigation in June and July in most years.
- Given current sugar prices and weather, the benefit from irrigation sugar beet in England is not sufficient to justify the cost of investment in irrigation infrastructure (boreholes, pumps, pipes, hose-reels, etc.) for sugar alone, but irrigating sugar beet in a dry June or July can be beneficial if water, equipment and labour are available.