tractor harvesting field
Following harvest and winter sanitation is an ideal time to make nutrient and soil amendment applications. (Photo: Alex Parsons, The Holloway Group)

By Brian Milne, Vice President, Director of Marketing & Communications, The Holloway Group

Harvest season is over, so it’s time to take some time off and get some much-deserved vacation time in, right?

Think again.

Now is the time to get back into the field, orchard or vineyard and ensure our soils and our crops are getting the irrigation, nutrients and amendments needed to ensure optimal health through the winter months on into next spring.

Harvest is an extremely stressful time of year for our crops, particular our trees and vines that were starved of water and nutrients for weeks, undergoing a strong “shaking,” or two, as harvesting equipment passed through to collect its bounty of nuts and fruit.

“The tree is played out at harvest. It’s tired. It’s done,” said Holloway Director of Agronomy Steve Lenander. “So, I like to come in with a big nutrition at that time, as well as whatever amendments we need. Because don’t forget, just because harvest is over, that tree is going through bud differentiation for next year’s crop. It’s starting to tell itself where the blooms are going to be next year. So, if you don’t have proper nutrition, proper irrigation, that’s going to be affected.

“You don’t want to forget about applications until the following year, and find yourself wondering ‘Why is my bloom so bad?’ Or, ‘Why was my set bad?’ Well, you forgot about that stress you had on the tree last fall when you went on vacation or something and forgot about it.”

Once that first post-harvest fertilizer application is taken care of, Lenander recommends growers assess soil samples and look at applying soil amendments such as gypsum.

So, when is the ideal time to apply gypsum, compost, and other amendments?

“The short answer is, I’d like to do it as early as I can in the year, post-harvest,” Lenander said. “But depending on the type of irrigation system that an orchard has, there are many cultural operations that have to be done first. For example, I don’t want to band gypsum and compost on, then have to come back and shake the trees, and sweep them, then you’re moving all of those materials out of the banded area you want those (amendments and nutrients) in.”

In almonds, for example, many growers are concerned with staving off navel orangeworm (NOW) this time of year, having crews go back through the orchard for winter sanitation purposes.

While every region and operation is different, mummy shaking typically takes place in November and December in the Central Valley, with growers preferring to shake in damp conditions during fog or a light rain in the morning, when nuts tend to fall off easier and NOW mortality rates are higher.

So, depending on the weather, winter sanitation can occur at different times depending on region, with South Valley growers typically starting to shake again by early December, versus growers in the North Valley who might wait until later in the year.

This can push back soil amendment applications until the first of the year, when the sanitation process is completed.

“I would like to have amendments on as early as possible so we can take advantage of winter rains,” Lenander said. “Plus, it’s just out in the field working, instead of sitting in piles. So we try to get it in as early as we can, but we have to think about the reality of cultural operations that happen and the ability to leave it in place where we need it up by the trees.”

The sooner the better for soil amendment applications, Lenander adds, so amendments and nutrients can move through the soil profile with winter rains, breaking up hard soils and breathing new life into the rootzone.

He also recommends taking soil, water, and tissue samples throughout the year, and addressing crop needs and deficiencies with amendments and nutrients in season.

“The trees don’t really sleep. We think they do, but they really don’t,” Lendander concluded. “They’re always doing something, even when they’re completely defoliated, they’re still working underground. So, the happier we can keep that tree, in all time frames, the better off we’re going to be when it comes to total yield.”

Interested in learning more about soil health? Watch videos about soil amendment application timing and other agronomy-related topics at

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