What is in this article?:
- Fall almond applications of zinc, boron and potassium
- Potassium deficiency
- Applying potassium through compost
- Plant nutrient levels are important, especially when heavier almond crops are produced.
- Nitrogen should not be added in late fall or winter due to leaching and potential loss.
- Potassium, foliar-applied zinc, and boron however, should be added if needed.
- Zinc sulfate can play an important role in breaking the disease cycle of rust and shot hole when applied as a foliar spray in November.
Applying potassium through compost
One of my favorite methods of applying potassium is through compost. While working with organic almond growers I came to appreciate the benefits of compost. Organic almond growers typically apply 10 tons of com-post per year in order to get their desired 200 units of nitrogen per acre (assuming 1.0 percent nitrogen in the compost). But when growers purchase compost they get a lot more than just nitrogen. A typical batch of compost (New Era) that I will use as an example had 1.32 percent nitrogen, 2.75 percent potassium, 1.45 percent phosphorus, 2.6 percent calcium, 0.5 percent sulfur, 1.16 percent magnesium, and 30.2 percent organic matter.
Assuming you are an organic grower applying 10 tons of compost per acre, you are applying 264 pounds nitrogen, 550 pounds potassium, 290 pounds phosphorus, 520 pounds calcium, 100 pounds sulfur, 232 pounds magnesium, and 6,040 pounds organic matter.
Our San Joaquin Valley soils are typically very low in organic matter and we know that it is a critical component of many nutrient cycles, especially the nitrogen cycle, so anytime you can increase your soil‘s organic matter you can increase soil fertility. I know many conventional growers that are applying compost, especially because of the added value and expense of potassium in addition to organic matter and other additional nutrients.
In light of Salmonella concerns, I recommend compost over the use of fresh animal manures. All composts are a little different, but they should come with a certified nutrient analysis and a statement that it has tested negative for Salmonella, E. coli, and Staphylococcus (bacterial pathogens).
From the certified nutrient analysis you can determine the nutrient value of the compost and rate you intend to apply. The compost analysis I examined had reached a high temperature of 152 F and averaged a thermophilic temperature of 140 F from 90 to 120 days. I would love to see more growers using compost and I believe the use of compost will enhance soil quality and ultimately orchard productivity.