Irrigation Alternatives for Sustainable Water Use of Processing Tomatoes
In 2010, excellent progress has been achieved in outreach and research on alternate furrow irrigation (AFI) in processing tomatoes. Collaboration between an industry leader, Campbell Research and Development, and the Jackson Lab at UC Davis was conducive to outreach to stakeholders involved in agricultural and environmental sustainability and tomato production. The 2010 field experiment under controlled conditions and similar agricultural management as commercial fields demonstrated the benefits that AFI may have for processing tomato in California. Results suggest that higher water use efficiency (yield/water applied) is possible without a decrease in yields. Further data analysis should help understand if plants under AFI regulate stomatal conductance more tightly without a decrease in photosynthetic capacity. The next step is a wider evaluation of AFI on growers’ fields to increase our understanding of plant responses to the interaction between irrigation and different environmental conditions, e.g., soil type, disease pressure and weather conditions. In this coming year, growers’ involvement in on-farm research will allow us to together assess the potential of AFI under real farming conditions.
- Increase the understanding of different furrow irrigation strategies among growers and evaluate the potential for adoption of alternate furrow irrigation as means of reducing total applied water, potential pollution and production costs. Evaluate water use and physiological, phenological and morphological responses of different processing tomato cultivars to controlled every or alternate furrow irrigation regimes. Obtain data on a soil water budget for every and alternate furrow irrigations and water depletion depths in the soil profile. Evaluate the effects of the every and alternate furrow irrigation regimes on nitrogen leaching and soil N2O emissions.
a) Several meetings, field days and presentations were held with different stakeholders through the year 2010 to discuss the potential for adoption of alternate furrow irrigation (AFI).
– Stakeholders involved in these meetings were: growers, UC Cooperative Extension specialists and farm advisors, researchers from UC Davis and the tomato industry, representatives from the Tomato Growers Association, NGOs and agricultural and environmental consulting firms.
– Presentation at the UC Davis Agricultural Sustainability Institute’s Russell Ranch Sustainable Agriculture Field Day 2010. Participation of about 50 people including growers, researchers, cooperative extension specialists and farm advisors, students, UC Davis faculty and the general public.
b) A field experiment was conducted during the summer 2010, in collaboration with Campbell Research and Development, to evaluate the response of three leading processing tomato cultivars in the region to AFI and every furrow irrigation (EFI).
– A complete randomized block design with a split block structure was set up to evaluate effects of AFI and EFI on tomato cultivars.
– Canopy growth was measured at different times from transplanting to harvest.
– Biomass evaluations were conducted at the beginning of fruit set and at harvest.
– Leaf conductance was monitored before and after different irrigation events.
– Leaf gas exchange measurements were taken during fruit set and filling.
c) Soil moisture data and water inputs as rain, sprinkle and furrow irrigations were measured and total water applied estimated.
– Soil moisture sampling to a three meter depth was done before transplanting and after harvest to evaluate if AFI and EFI affect soil water depletion.
– Water inflow through furrow irrigation was measured at the pipe gates of every furrow, and total water applied was estimated for each irrigation event.
d) Soil nitrogen sampling.
– Anion exchange resin bags were placed before transplanting at 75 cm depth to evaluate nitrate leaching from the fertilizer applied in the planting beds. Resin bags were removed after harvest.
– Soil sampling, for mineral N, nitrate and ammonium, was done three times during the season to a 75 cm depth.
– Gaseous emissions of soil nitrous oxide (N2O), a potent greenhouse gas, were spot sampled a day after most irrigations when soil gas emissions should have been the highest.
Impacts and Contributions/Outcomes
- High interest on the potential of AFI to increase water use efficiency (see below) and contribute towards more sustainable farming practices has been shown by stakeholders from the tomato industry, NGOs and extension personnel during field days and meetings. The next step is to conduct experiments in growers’ fields and, under their management, to evaluate AFI under real on-farm conditions. Results from the 2010 field experiment show an increase of nearly 25% in water use efficiency without a decrease in yields. Total applied water to the every furrow irrigation plots was 42.4 cm while tomatoes under AFI received 31.6 cm. Yields were similar to what it is obtained in commercial fields, 113 Mg/ha (50 tons/acre). The decrease in water applied did not affect canopy growth and aboveground biomass.