Addressing Soil Fertility under Saturated Conditions
This winter brought heavy precipitation, and with it came welcome water storage, soil profile recharge and salt leaching. However, challenges related to saturated soil conditions have also surfaced.
The comparatively high-water volume may have leached nitrate in your almond orchards more than recent years; thus, soil nitrogen status may be an important consideration. Saturated soils can favor denitrification, a process where anaerobic bacteria convert nitrate to gaseous forms of nitrogen. It should be noted that initial nitrogen applications may be eliminated or rates reduced when soil nitrate levels are greater than 20 ppm. Dividing up the seasonal budget, utilizing Coron® Metra, with more frequent and lower application rates, improves use efficiency, studies show. Foliar nitrogen, though limited in total volume of the seasonal budget, can be a highly efficient method of maintaining nitrogen levels during critical periods before leaf reporting can be accomplished. Studies have shown the benefits of crop development with Coron Metra. Whatever the approach, it is worthwhile to take additional soil samples and review the results with your Helena consultant leading up to spring. This will best prepare your orchards for root flush and leaf-out.
In addition, under flooded soil conditions, phosphorus may have been depleted and availability is highly dependent on soil microbial populations. Hydra-Hume® from Helena can improve soil nutrient cycling and is an important addition to soil amendment programs. Hydra-Hume helps maintain soil structure, increasing resiliency to both flooding and drought conditions as well.
Another nutrient challenge presented by saturated soils is potassium. Potassium (K) is a nutrient that can be challenging, particularly in soil with a low nutrient-holding capacity or clays that tend to fix K. Potassium fertilization practices generally depend on long-term soil storage, and thus requires consistent applications to maintain available levels. However, with the high cost of fertilizers, maintenance of these levels can be a challenge. Therefore, in addition to spring soil sampling, Helena recommends sampling leaves as soon as possible in preparation for in-season fertilizer applications and follow-up with additional sampling to confirm practices as necessary. Nitrogen inputs need to be balanced with potassium to avoid limiting yield potential. As a reminder, K plays an important role in water relations and disease resistance in the plant. K is also important during critical periods of development and during extreme temperature changes.
While the winter rains were a welcome sight for almond growers, it is important to keep in mind how they will impact your orchard this season. For more information about the impact of saturated soils, contact your Helena representative to build your Almond Wise program today.
- Jon Thornton, Western Division Agronomist