Solution Center for Nutrient Management
Solution Center for Nutrient Management
Solution Center for Nutrient Management
University of California
Solution Center for Nutrient Management

Mark Mason - Huntington Farms

Overview

Mark Mason is the manager for Huntington Farms, a third-generation family business in the Salinas Valley, responsible for farming head and leaf lettuce, cauliflower, celery, and broccoli on 4000 acres of land in the Soledad-Salinas area. The fields are generally double cropped per year. He has been at his current position for six years and has worked in other cool season vegetable production enterprises in California before that.

Mark Mason
Mark Mason

For the last 2 -3 years Mark has been working with Michael Cahn, UC Cooperative Extension Farm Advisor in Salinas, to implement CropManage, an on-line irrigation and nutrient management tool. CropManage has been developed by Michael Cahn to improve water management and match nitrogen (N) applications to crop N uptake. The web application uses the soil nitrate quick test results and weather-based irrigation scheduling, in addition to site and planting specific information, as data inputs and allows managers, irrigators, and fertilizer staff to allocate and coordinate resources with the goal of minimizing potential leaching losses of nitrate.

http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=8501

Motivation to Improve Nitrogen and Water Management

Mark’s motivation for working with the CropManage tool was initially to save on nitrogen fertilizer costs and ‘do-the-right-thing.’ Eventually though, Mark believes, the reward for farming sustainably is the guarantee that there is a market for the produce he grows. Big buyers of cool season vegetables demand certain standards, such as minimal pesticide use, but presently one buyer is also insisting on fertilizer limits. Aside from industry pressure, Mark was interested in better controlling N fertilizer pollution because he enjoys working with UC extension specialists and has in the past benefitted from the interactions with scientists, for example in the field of pest control.

Water and nitrogen management “go hand-in-hand,” Mark is convinced. “They cannot be managed independently of each other. If we over-irrigate, nitrate is leached out of the root zone, and as a result greater fertilizer applications are required, so we should always apply the correct amount of water.”  To germinate lettuce, a significant amount of water, about 6 inches, is applied with sprinklers, first every day for four days, and then every other day. Less water (about four inches) is used if subsurface drip irrigation (with shallow drip tape placement) can be employed, which is possible in soil types where water rises to the surface. Surface drip is often used once the crop is established and thinned. Typically, Mark fertilizes lettuce twice, a first N application once a stand is established and another one after three more irrigations.

Irrigation Challenges

Managing irrigation and nutrients in hundreds of temporally staggered 10-acre plantings requires careful planning, a reliable communication system among irrigation and fertilizer managers, irrigation equipment in good working condition, and knowledgeable irrigators. Drip irrigators must know a lot to effectively control water applications. They have to keep the pressure correct, be able to fix leaks, and set up runs of adequate length. If the tape gets stretched out, emitters are damaged, leaks occur, and the whole operation becomes inefficient. In practice, by the time an irrigation order from the irrigation foreman to the sprinkler irrigation foreman is executed by a worker, the actual amount of water applied is often considerably larger than planned because employees do not want to be responsible for under-applying water to crops. This is one of the problems the CropManage tool addresses.

Advantages and Challenges of Using CropManage

CropManage recommends irrigation amounts based on crop stage, soil moisture, and weather variables, and managers and foremen directly enter the actual irrigation amounts (translated into hours of irrigation). Because CropManage is an online tool, the actions of all users are recorded in a single place. If there are deviations from the recommended quantities, everybody involved in the management knows what the changes were and who has made the decisions, and the program adjusts before the next recommendation. Human error, e.g. forgetting to input data, can throw the whole system off and weaken the usefulness of the CropManage tool. Traditionally, irrigators have decided how much water to apply ‘by experience,’ but the goal is to follow the CropManage recommendations. At this point, Mark does not have enough confidence in the data collection to use CropManage as the sole decision tool. He trusts the program to generate the correct recommendation, but he does not yet fully trust the data collection and recording on his farm.

Once the inputs are reliably entered by everybody, CropManage should work very well. Mark Mason and Michael Cahn are still working on perfecting the app and educating the managers and foremen. Mark has no doubt that the goal of having about 20 people with tablets synchronized with the master data base he oversees will be realized soon. As of now, the ranch organization has already come a long way from the days when a staff person in the office kept up irrigation records based on notes handed in by field managers. For 2017, one person has been designated to exclusively engage in ground-truthing all entries into the data base.

Soil sampling is one of the linchpins of the CropManage tool. The program recommends fertilizer applications based on the nitrate concentration in a composite soil sample taken from one foot-deep cores. Mark takes 6 cores per 10-acre field at each sampling. Instead of the nitrate test strips, which he thinks “everybody interprets slightly different,” he is using an instrument to measure nitrate concentrations in the soil extracts. Most importantly though, Mark does not trust a single measurement just before a planned N fertilizer application to reliably indicate a field’s N availability. In 2017, he plans to sample every field once a week to determine trend lines of nitrate concentration. He expects to see soil nitrate levels decline before fertilizer applications and wants to make fertilizer decisions based on the perceived trends. He is generally using liquid synthetic N fertilizers (urea ammonium-nitrate and ammonium thiosulfate) and dilutes the fertilizer material in the tanks on the tractors, if necessary, to avoid having to recalibrate delivery rates.

Adjusting synthetic N applications is straightforward compared to accounting for the nitrate in the irrigation water. There are 12 wells on the ranch with widely different nitrate levels, ranging from very high to near zero nitrate concentrations. The same field may be irrigated with water from several wells, and irrigators sometimes have to switch from one well to another in the middle of the night. To measure N inputs via the irrigation water, Mark has to keep track of which wells are used and the duration of time for each field, which is quite a challenge, but he is confident that even this data entry will eventually be reliable. He is committed to make CropManage work.   

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