Mario Miranda Sazo

For seeding in late June/early July, there are really only two cover crop choices at this time: One is sudangrass, or sorghum-sudangrass, and the other is buckwheat. Both grow rapidly in the summer warmth. Growers who are planning to plant a new orchard site (or a replant site) next year can consider the use of cover crops before planting an orchard. Their benefits are numerous. When used they can:

• improve organic matter
• break up compaction layers in the soil profile
• suppress weeds
• control erosion

Sudangrass and buckwheat have different properties, so the management goal and field condition will determine which is the right crop for you:

Sudangrass is often chosen for improving soil organic matter. It produces a strong root system and lots of biomass. The deep root system helps reduce subsurface hardness. Sudangrass is also a good choice for reducing root-knot nematode pressure.

• Sudangrass is suitable for short, 8-10 week plantings. Seeding rates are 30 lbs/acre for biomass and nematode control and 50 lbs/acre for weed control.
• Seeding rates are June through mid-August (for sudangrass).
• Seeding rates are July through mid-August (for sorghum-sudangrass).
• This grass grows very fast, so keep an eye on it. Mow the first time when it reaches 3 feet and the second time while the flail mower can still chop it well.
• If sudangrass gets too big to control, it will be killed by frost and make a nice winter mulch. However, the biofumigant effect will be lost.
• Sudangrass needs a final flail mowing and immediate incorporation to suppress nematodes.
• We have seen good results with the additional strip-seeding of radish tillage (by the end of August/early September) in the future in-row spacing of an orchard to be planted the following spring.

Buckwheat is best known for weed suppression and mellowing the soil. It covers the ground earlier than sudangrass, especially if seeded in early June, and outcompetes weeds that may establish in sudangrass. Sudangrass requires a higher seeding rate for effective weed suppression.

• Both cover crops should be mowed after about 40 days. This is the end of the season for buckwheat, but the beginning of major root growth for sudangrass.
• To avoid volunteer buckwheat seed, kill the crop before there are filled green seeds on the plant. This takes about 40 days from a July planting or 50 days from a June planting.
• Buckwheat seed is available from some local farm seed retailers and is relatively cheap. The variety does not matter, and many suppliers don’t identify any variety. A bag is enough to seed an acre.

You can also improve soil water holding capacity and nutrient availability by improving your soil organic matter content for more sustainable apple production. Organic matter tends to act like a sponge, holding water and nutrients in the soil and releasing them slowly over time. Soil scientists report that for every one percent of organic matter content, the soil can hold 16,500 gallons of tree-available water per acre of soil down to one foot deep.

• Increased water holding is an important characteristic in our NY soils. It is even more crucial in blocks without trickle irrigation. At the beginning of this 2023 summer, a mature spindle tree needs around 4-5 gallons of water per day to keep up with tree evapotranspiration needs. Water stress can lead to small-sized fruit and calcium disorders, like bitter pit in Honeycrisp. Young trees need only small @ 2-3 gallons/tree/day, 2-3 times per week, but frequent doses of water for additional tree growth this year.
• Soil organic matter acts like a bank for soil nutrients. Think of each of the negative charges on an organic matter particle like a parking spot for a nutrient ion. Cationic nutrients, such as calcium (Ca2+), are parked and ready to be knocked out into the soil solution where tree roots can access them. Root exudates from tree’s rootstocks help “knock” nutrients into solution by trading these nutrients (such as calcium) with hydrogen ions. The higher the cation exchange capacity (CEC), the more of these parking spaces for nutrients are present in the soil. More nutrients can then be held instead of being washed away into deep soil layers where trees cannot access them.
• Organic matter not only banks nutrients but also supplies nitrogen through mineralization. Organic matter contains about five percent nitrogen, and two to four percent of this is mineralized every year. For example, a soil with three percent organic matter can make available sixty pounds of nitrogen per acre every year (as long as soil organic matter is maintained).