- Vegetables: tomatoes
- Production Systems: general crop production
Alternative irrigation methods that use less water, but produce high yields, contribute to agricultural sustainability. This project focuses on the promising partial root drying (PRD) technique used in practice as alternate furrow irrigation, to reduce water applied and increase crop water use efficiency (yield/water applied, WUE) of processing tomatoes in California. Information is now available on general crop physiological responses to the PRD technique, but strategies for reliable management need to be tested for individual crops. Alternate furrow irrigation consists of selectively watering only every other furrow. Each bed receives water on just one side, and alternates the sides/furrow at each irrigation. Using half of the furrows in a field can reduce the volume of water applied, potentially without a decrease in yield. Our research approach will engage growers from the start of the study to address the main concerns raised about alternate furrow irrigation, e.g., crop yield and costs. Furrow irrigation is the principal irrigation method in California. About 80% of tomato fields are furrow irrigated, and it is the largest cost of field operations before harvest in processing tomato production. We will survey growers who use this innovative practice, and conduct an on-farm case study and field experiments to evaluate effects in field-grown processing tomatoes. We estimate irrigation reductions of about 30% considering that up to 50% reduction can be achieved in other crops, and that this project will eventually cause irrigation reduction on >30% of the processing tomato acreage, partly instigated by the risk of drought in California now, and with future climate change.
Project objectives from proposal:
Objective 1. Conduct an on-farm case study to obtain data on a typical soil water budget and cultivar responses with alternate furrow irrigation.
Hypothesis 1: Plant water stress may be encountered during peak activity of fruit set and development, and this may be an important period for fine-tuning the timing and amount of water with alternate furrow irrigation.
Objective 2. Evaluate water use and physiological, phenological and morphological responses of different processing tomato cultivars to controlled full or alternate furrow irrigation regimes.
Hypothesis 2a: Root development and soil water extraction may increase under alternate furrow irrigation, while vegetative shoot growth may be reduced and yields remain constant.
Hypothesis 2b: Less total water may need to be applied to produce high yields during the crop season under alternate furrow irrigation, compared to full irrigations, and thus WUE may increase while runoff may be reduced.
Objective 3. Increase understanding of PRD and alternate furrow irrigation management among growers as means of reducing total applied water, potential pollution, and production costs.
Hypothesis 3: A survey of farmers who use alternate furrow irrigation will provide a necessary basis for orienting outreach and education efforts to a much larger group of stakeholders in the region.