Planting Peanuts

A few growers have started planting peanuts late this week as subsoil moisture comes more of an issue. Most growers will want to pull the trigger next week. We’re planting right now with some fungicide and inoculant in furrow. Here is a few pointers from UGA Extension Agronomist, Dr. Scott Monfort and Dr. Scott Tubbs:

Soil Temperature

It is recommended that the average daily soil temperature remain above 68 degrees for 3 consecutive days and without cold temperatures in the forecast for the next week before making the decision to start planting peanut. With a warm winter so far, the temperatures had been in the “acceptable” range of conditions … during the last week of March.

armer temperatures are expected to return during the week of April 10-16, and I anticipate the 4-inch soil temperature will warm quickly to a point acceptable for planting by the middle of that week. There are no other cool spells showing in the extended weather forecast through April 21, so I anticipate peanut planting should be in favorable conditions sometime next week including adequate soil moisture because of this past week’s rainfall.

It is important to watch for additional rainfall in the forecast, especially under non-irrigated conditions, in order to activate herbicides after planting. Even with soil temperatures above 68 degrees, it will often take peanuts 7-14 days to emerge from the ground in these conditions (with cooler night temperatures still causing some fluctuations in soil temperatures). In ideal conditions, growers would want to plant with adequate moisture, sustained 68 degrees at the 4-inch soil depth, no cool temperatures expected in the 10 day forecast, but some rain expected within one week of planting in order to ensure optimal peanut emergence and herbicide activation to give the best possible growing conditions from the beginning. Hopefully we can get some peanuts in the ground a few days on either side of Easter this year and catch a rain the following week to get this season off to a great start.

Inoculants

Last year was a very hot and dry year. In those conditions, the survivability of the living Bradyrhizobia bacteria needed to inoculate peanuts is generally reduced. Thus, there may less than adequate nodulation of peanut in some fields or some parts of fields if relying solely on native soil Bradyrhizobia to infect the roots of peanut for N-fixation this season. This is true even if planting in short rotation where peanut was planted within the last few years.

I would recommend growers strongly consider the investment in a peanut inoculant at-planting this year, especially in fields that did not have any cover crop residue on them last year to minimize direct heat impact and reduce evaporation of soil moisture in the upper portion of the soil profile. It has been stated before by my predecessors and colleagues, an inoculant application is one of the most cost-effective “insurance policies” at a grower’s disposal.

Depending on the product used and contract price received for peanuts, it usually takes in the neighborhood of 100 lb/ac yield increase to cover the cost of the product. It is common in my research trials and in reviewing research from colleagues to get greater than 100 lb/ac yield increase on average over multiple years of trials even in a standard rotation. More importantly is to consider the cost of NOT applying an inoculant and having a nodulation failure where there is not adequate N-fixation. The cost of applying the amount of N needed by peanut would greatly exceed the cost of applying an inoculant over the course of many, many years. The risk of not getting a return on investment for an inoculant compared to the risk of potentially losing a large proportion of yield potential one year is not an equal level of risk in my opinion.

Keep in mind that the product is listed on the label to be delivered at around 1.0 fl oz per 1,000 linear row feet (may differ slightly depending on which product is selected). This is developed for single row application! Inoculant application is not like adjusting seeding rate, where you are pulling half of the amount out and moving it over to the adjacent twin furrow. With an inoculant, the applied amount needs to be per furrow according to label instructions. Therefore, a twin row planting inoculant application will double the amount of inoculant applied compared to a single row planting. I have no data at this time to support using a half-rate of inoculant per furrow to keep the total application rate per acre the same as a single row planting.

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