C A L I F O R N I A
Vegetables A SPECIAL GROWERS’ REPORT OF AG ALERT ®
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A University of California specialist has been conducting a long-term study of growing tomatoes using four different management systems. UC specialist Jeff Mitchell says the system that combines no-tillage methods with cover cropping improves water infiltration into soil.
Advisors describe soil-building actions for tomatoes ByBob Johnson
anacre to the soil. That included15 tons of carbon, which is attracting greater interest as re- searchersandregulatorscometoseetheimportanceof soilpractices toslowclimatechange. Theno tillageandcover cropsystemalso reduced toa small fraction theamount of time it takes for 1, 2, 3or 4 inchesofwater to infiltrate into thesoil,whichMitchell said translated into a significant increase in the ability of the ground to storewater. Healthy soil hasmore stable aggregates, he said. There is a free smartphone app called Slakes that will take a 10-minute video of a soil sample after it is put into water and give a soil stability rating based on how quickly the soil dissolves. Soil in the no tillage with cover crops system for the last 20 years at Five Points has the greatest stability,Mitchell said, whilegroundmanagedwithstandard tillageandnocover crops has the least. “The goal of soilmanagement is to increase thedepthof the layer of improved soil over time,” he said. Althoughchanges in the soil fromregenerativepractices tend tobe slowand long term, researchers are also studying the more immediate benefits of adding compost to the ground before a tomato crop. UC Cooperative Extension farm advisor Scott Stoddard studied the application of See TOMATOES, Page 12
Long-termmanagement programs that include reduced tillage, cover crops and com- postmaybe thekeys torestoringorbuildingsoil thatwill producegoodyieldsofhigh-qual- ity tomatoes in the decades to come, researchers say. University of California specialists say the improvements that come from these soil-building practicesmay be subtler and slower than the impact of applying chemicals, but the changes are real and beneficial. “The soil in the no till and cover crop systems givesmuch faster water infiltration,” UC Cooperative Extension specialist Jeff Mitchell said. “You can reduce summer evapora- tion over time. On balance, the cover crop has also sequestered a considerable amount of carbon.” As the leading expert in theUCsystemonconservation tillage,Mitchell has supervised adecades-long studyof the impact of growing tomatoes at theUCresearchandextension center in Five Points, using four different management systems—conventional, a green manure cover crop, no tillage, and no tillagewith a cover crop. He discussed the results of that long-term experiment as other UC researchers also reportedon shorter-termcompost studies during the 2021CaliforniaProcessingTomato Production virtual workshop. In 20 years at Five Points, Mitchell said, the cover crops added 32 tons of organicmatter
March 17, 2021 Ag Alert 11
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