Water is a limited resource. According to FAO, agriculture is the world’s largest consumer of water. Between now and 2050 the world’s water supply will have to feed and create livelihoods for an additional 2.7 billion people. It is essential to identify ways to preserve this precious resource.
By making key changes in irrigation and fertigation practices, Monsanto Hawaii’s production research and manufacturing teams have saved more than 11 million gallons of water or enough water for more than 150 households for a year.
The research team undertook a series of studies at the Molokai and Kunia locations in Hawaii to better understand the movement of irrigation water in the soil profile and its uptake by the crop. Previously, irrigation had been managed on a pre-determined schedule. Crops were being irrigated at set intervals, with multiple short durations and frequent intervals.
Consequently, water wasn’t used efficiently and many nutrients applied through fertilization processes were being lost.
“Water is a valuable resource in Hawaii, and it appeared the plants were not rooting down into the soil profile due to over watering,” Steve Christensen, Monsanto Hawaii production research scientist, said. “Without an adequate rooting system, plant uptake of fertility was only occurring in the top few inches of the soil profile. Fertility is closely tied to water movement, and leaching of nutrients beyond the plant rooting zone was occurring. This was allowing portions of the fertility to be unavailable throughout the growing season and potentially leaching into the aquifer.”
By learning more about water use by crop stage and recent rainfall or current weather conditions, the team was able to implement new procedures to save water. The team changed the standard irrigation schedule from three short times a week to one longer irrigation event per week, making water use more efficient. Combining the new irrigation practice with a new reduced fertilization schedule made nutrients more available to the crop with less leaching. The improvements also significantly reduced manual labor on the fields.
“Irrigation generally requires at least one person to visit the field twice per irrigation event,” Michael Nagel, Monsanto Hawaii manufacturing lead, said. “This is necessary to check for and repair leaks. In many older plantation era systems, where it is either impractical or impossible to apply automation, it is also necessary to manually open and close the valves at the beginning and end of the irrigation event. By reducing the number of irrigation events from two or three times per week to one, the labor requirement was effectively reduced by one-half to one-third.”
As the team continues its research, there are opportunities to build on these results. Agronomic conditions like soil type and the amount of water lost to evapotranspiration vary between farms, providing an opportunity to continue the research at the rest of Monsanto’s locations statewide. Work is already underway to refine the irrigation programs at other farms on the island of Oahu and other sites in Hawaii. Eventually, the team hopes to develop a true on-demand irrigation system, which could save even more water and labor.