California Agriculture

California processing tomato growers must adapt their irrigation management practices to cope with frequent droughts and increasingly limited groundwater supplies. Processing tomatoes’ water stress tolerance provides a water savings opportunity through deficit irrigation. However, it is important to initiate deficit irrigation at key growth stages to maintain yields. We conducted a deficit irrigation experiment over three years using a randomized block design with four treatments in three commercially operated fields in Fresno County. A tapered deficit treatment was applied, where the amount of water deficit was increased partway through the deficit period to ease the crop into higher water stress while further reducing irrigation. In all three seasons, there were no differences between treatments in yield, with some seasons having an improvement in Brix with the higher deficit treatments. This was achieved with up to a 29% reduction in irrigation compared to the grower’s standard practice. The results of this study suggest that tapered deficit irrigation can be a viable option for optimizing water savings in processing tomato systems.

In an increasingly unstable climate, it is critical to optimize water needed for crop irrigation to secure food production and livelihoods while reducing environmental impacts. Here, we focus on water use for almonds — a crop that occupies roughly 20% of the irrigated agricultural land in California and has long been the focus of scrutiny. Regenerative agriculture, a term used to describe system designs that increase soil health, biodiversity, resilience to climate, and profitability while reducing greenhouse gas emissions, water use, and pollution, offers a potential way forward. We used eddy covariance, micrometeorological, and soil moisture measurements from 2022 and 2023 to quantify the evapotranspiration of California almond orchards under different soil and plant management practices and produce comprehensive estimates of the water footprint of different management systems. In five almond orchards, we find that there is little difference between evapotranspiration at regenerative and conventional sites in winter months, and that regenerative sites have similar or slightly lower evapotranspiration during the growing season. Orchards with cover crops had higher infiltration rates of winter precipitation than those without; however, soil moisture did not differ between management types. This case study demonstrates that regenerative management in almond orchards leads to improvements in soil moisture retention without guaranteeing increased evapotranspiration.