Watering Peanuts

How much water do my peanuts need? Gary L. Hawkins, John Beasley & Calvin Perry, UGA College of Ag Scientists

 The following graph is  reproduced from the UGA Bulletin #974 “Irrigation Scheduling Methods” by Kerry  Harrison.   This curve represents the  average daily water use by peanuts over the life of the crop.

In UGA Bulletin #974 there is an explanation and example of  how much and how often water should be supplied to the plants.  There are also two methods of calculating  water application amounts and days between applications (The Water Balance  Method will be used for an example in this article).  Water can be added either from rainfall or  irrigation if available.  Here I would  like to go through an example to provide a different soil type other than that  listed in the bulletin.  In this example  I will use the soils in the Decatur/Mitchell County Area.  Information to use in calculating the needed  water comes from three different locations:   The County Soil Survey books produced by the USDA-NRCS, the Web Soil  Survey (http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm)  and the Georgia Weather Net (http://www.georgiaweather.net/).

For the Water Balance Method, let’s assume a Blanton Soil  Series, 24 inches is the rooting depth (be aware of hardpan depth), the total  available water is 1.92 inches (from the Soil Survey book, Table 16 or the Web  Soil Survey under the following tabs -“Soil Data Explorer”, “Soil Properties  and Qualities”, Soil Physical Properties”) and let’s assume a 60 day old  crop.

Step 1:  Determine from the amount of required water from  water use curve, from the curve we will need 0.19 inches per day.

Step 2:  Determine irrigation by setting lower limit  for water balance.  For this example we  will use a 50% limit (the crop only uses half of available water before  replacing).  So if the available water in  the 24 inch root zone is 1.92 then we will work using 0.96 inches will need to  be replaced.

Step 3:  Determine amount of irrigation by accounting  for irrigation system efficiency.  For  this example we will use 75%.  The amount  of water to be applied is 0.96/0.75 = 1.28 inches or 1.3 inches.

Step 4:  Determine frequency of irrigation by dividing  amount needed by water use per day.  For  this example the frequency will be: 0.096/0.19 = 5 days.

Step 5:  Therefore it is necessary to apply 1.3 inches  every 5 days to maintain 50% available water on Peanuts that are 60 days old.

So from the included curve and knowing the day after  planting the amount of water needed to replace the water used by the crop can  be calculated and if irrigation is used what frequency will need to be used  when applying water.  The application  rates and frequency of running the irrigation system should also be based on  the amount of water added to the soil profile from natural precipitation by  accounting for the inches of water applied via rainfall.

One last note on knowing available water in the soil  profile, the farmer should consider using some form of soil moisture  measuring.  Three available methods  include the use of tensiometers, electrical resistance meters or capacitance meters.  Two of these three are explained in the UGA  Bulletin #974.  The soil moisture meters  will allow the farmer to have a better idea of what moisture is available and  should provide some guidance on available water and irrigation needs.

Other methods of helping schedule irrigation is the UGA Easy  Pan method (UGA Bulletin #1201), the Irrigator Pro program developed by  USDA-ARS and many of the irrigation companies now have some form of irrigation  scheduling methods available.

Overall, knowing what the plant needs along with what can be  supplied from rainfall or irrigation can help the farmer supply ample water to  the peanuts while not wasting water.

Growth Stage-Water Curve

 

          A good method for irrigating peanut is a modification of  the original UGA recommended irrigation strategy of applying 2 inches of water  per week (minus rainfall) starting once peanut plants initiate blooming. In the  modified version we follow the water curve for peanut and apply less water  during weeks 5-6 (early bloom) and 7-9 (early pegging) and wait to apply  maximum water rates (1.5 – 2.0 inches per week) for peanut in weeks 10-17 (peak  pegging, pod fill). In weeks 18-20 we back down on the amount of water. During  this time of the growing season we do not want to over water for fear of initiating  limb rot. In the last three weeks we want to eliminate drought stress that can  increase risk of aflatoxin. Here is a schedule for the Growth Stage-Water Curve  (Modified UGA Extension) Irrigation Strategy:

Irrigation amount  (inches) per week for peanut.

Weeks    of Growing Season	1.5    inch maximum	2.0    inch maximum
5-6	0.5	0.75
7-9	0.75	1.0
10-12		1.5
10-17	1.5
13-17		2.0
18-20	0.5	0.75

We researched it at a 2-inch maximum and a 1.5-inch maximum.  The reason for that was we know there are some growers that have fields that  can’t receive one-inch of water without excessive runoff. Therefore, we tested  it with two applications of 0.75 inches twice a week and two applications at  1.0 inches twice a week. In the table below are the 1.5 and 2.0-inch maximum  strategies in case any of your growers want to use this strategy for irrigating  peanut.

The key in early season irrigation on peanut is to not apply  too much water. Be judicious with early season irrigation events and save them  for later (weeks 10-17, or days 70-126) in the season when the water demand is  higher. This is especially true for producers irrigating from surface water  resources.  We just don’t  need to water the crop too much early. The water demand curve indicates the  requirement is low prior to peak pegging and pod fill.

However, if you want more vine growth then the water the peanuts get the first 30 days will do a lot to promote larger vines.

Calvin’s Winter Irrigation Jobs

Winter Irrigation Maintenance:

With our summer crops harvested and out of the way, now is a good time to look at maintenance

of our center pivot irrigation systems. Here is a checklist of items to consider from Calvin Perry, UGA Ag Engineer:

Perform a “catch-can” uniformity test to verify the system is applying water uniformly.

Check for leaks, malfunctioning or missing sprinklers, etc. Repair problems.

Drain pipes, valves, tanks, pumps, sprinklers, booster pumps, etc.

Close or cover openings, even with motors and pumps, that would allow mice to

enter.

Service gear boxes, drive lines, motors on pivot towers, as well as the engine that

may be driving your pump.

Lock the control box in the OFF position.

Repair deeply rutted pivot wheel tracks.

Consider a new sprinkler package that could replace what’s on your system now, if it’s

not performing well. There are many new, innovative sprinkler designs on the market.

Make sure the flow meter on your withdrawal point (usually at your pump) is

functioning properly and look at your flow meter readings and see if your pump is

putting out the flow that it’s designed for.

And it’s also a good time to think about next year. You’re not quite as busy this time of

year, so give some thought to

Do I want to look at a different irrigation sprinkler

package?

Do I want to look at some new technologies to help with irrigation scheduling?

Or look at some sensors and maybe software that could help with that technology?

Irrigating Cotton

Cotton Incorporated has a new cotton irrigation publication on its website. Our UGA Stripling Irrigation Park in Camilla and Ag Engineer and Director there Calvin Perry, had a part in this publication. Here’s some info concerning it and here’s the link to go to it.

http://www.cottoninc.com/fiber/AgriculturalDisciplines/Engineering/Irrigation-Management/

Irrigation Management for Humid Regions

 Use of irrigation has been increasing across the humid areas of the Cotton Belt for the last 20 years. While there is a large collection of information for irrigation management related to cotton in arid regions, information specific to management under humid conditions is not as well developed. Therefore, the objective of this publication is to provide producers with an overview of the technologies available to schedule irrigation and key concepts related to water management for cotton grown in areas where rainfall provides a significant amount of the water requirements in most years.

This document is divided into nine sections that address a variety of topics including: the benefits of irrigation and why water management is important; cotton water requirements in humid areas; growth stages that are sensitive to water stress; and a review of tools for irrigation scheduling. An overview of different methods to deliver water to the field is also provided.

Irrigation water, if managed wisely, is an important tool to optimize productivity of the land and to ensure that no other inputs go to waste. Thus, it is an important tool that can be used in developing a sustainable crop management strategy. Granted, there is great competition from urban and industrial water users, even in the water-rich Mid-South and Southeast, but it is the authors’ hope that by using the knowledge presented here every drop of water applied to cotton will be used beneficially.

 Here’s a list of the different sections in the publication:

▸ Why Irrigate Cotton?

Irrigation Stabilizes and Boosts Yield

Removing Risks Associated with Yield Instability

Why Plants Need Water

Seasonal Water Requirements Vary by Climate

Plant Response to Water Stress

The Relationship Between Water and Yield

Water Use Efficiency

Increasing Water Use Efficiency

Boosting Yield and Reducing Costs

Optimizing the Use of All Crop Inputs

Getting the “Most Crop Per Drop”

▸ Why Schedule Irrigation?

The Risk of Too Much Water

Proper Irrigation Methods

Plant Available Water

Results of Water Loss

Estimating the Soil’s Ability to Provide Water

Signs of Water Stress

Targeted Irrigation Scheduling

The Art and Science of Irrigation Scheduling/p>

▸ Initiating and Terminating Irrigation for the Season

When to Initiate the First Irrigation

Irrigation Near the Time of Emergence

When to Apply the Last Irrigation

▸ Cotton Water Requirements

Evapotranspiration

Measuring Evapotranspiration

Water Use

Water Use and Crop Coefficients

▸ Water-Sensitivity of Cotton Growth Stages

Planting to Emergence

Emergence to First Square

First Square to First Flower

First Flower to Peak Bloom

Peak Bloom to Open Bolls

▸ Sensor-Based Scheduling

Types of Measurements

Types of Sensors

Costs and Methods of Obtaining Soil Water Data

Decision Factors

Cost Factors

Locating Sensors

Irrigation Scheduling

Types of Irrigation Systems

Access to Sensors

Sensor Installation

Compatibility with Field Operations

Connecting Wireless Systems

Interpreting Sensor Results

Accuracy of Sensor Readings

Retrospective Use of Sensors

Using Post-Season Soil-Water Data

▸ Irrigation Scheduling Tools

Water Balance Method

Soil Water Content

Maintaining Soil Water

Estimating Crop Water Use

The Mississippi Irrigation Scheduling Tool – MIST

The MOIST Program (University of Tennessee)

Combining Soil Moisture Monitoring with Water Balancing

▸ Management Considerations for Irrigated Cotton

Cotton Crop Irrigation Increasing

Germination and Seedling Emergence

Pre-Squaring Cotton

Squaring Cotton

Early Bloom Cotton

Cutout, Late Bloom and Boll Opening Cotton

General Irrigation Management Considerations

Irrigation Adds Flexibility to Farming Operations

Irrigation and Variety Selection

▸ Irrigation Systems Overview

Subsurface Drip Irrigation

Surface Drip Irrigation

Center Pivots

Surface Irrigation (Flood/Furrow)

Irrigation Water Quality

Irrigation Well Suspension Meetings

Issuance of Agricultural Water Permits has been suspended in parts of Georgia until November 2013.  To help answer some questions concerning the reasons why this occurred, how farmers can help conserve water, and what are the next steps, a couple meetings have been organized as shown below to inform farmers and others interested in water permits in Georgia. 

  

Dates, Location and Times

December 4, 2012 – Mitchell Co. Ag Building, Camilla, Ga

December 12, 2012 — Terrell Co. Govt. Building, Dawson, Ga

 

Registration — 8:30 – 9:00 AM and Adjourn by Noon

 

There is no registration fee, but to ensure we have room for all participants, PLEASE call 

229-386-3377 

And let them know you plan to attend.

Soybean Irrigation

Soybeans need water when they need it and they are not very forgiving when they don’t get the moisture that they need for filling the pods. Our Ultra Late Soybeans are in a time frame when they need lots of water.  Some of the traditional irrigation recommendations were based on wilting of the soybean crop, especially during early reproductive growth.

It’s very likely that when the soybean plant wilts, yield potential can be lost and the degree of loss has to do when that stress occurs, according to Jared Whittaker, UGA Extension Crops Scientist.

The degree of loss is related to soybean development during which that stress occurs. Specifically, when wilting occurs during reproductive growth the chance for lost yield potential can be much greater than if it were to occur during vegetative growth. Therefore, one way to potentially modify the old system would be to irrigate to prevent wilting from 1st bloom(R1) until full seed (R6) instead of just between R5 and R6.

Temperatures during early reproductive growth also likely play a large role in Georgia soybean yield potential. High temperatures during early reproductive growth (R1 through R3) can significantly reduce flower and pod retention, often negatively impacting yield. There are two ways in which proper irrigation could help alleviate these effects. First, proper irrigation prior to bloom can help to ensure canopy closure, and that shading may potentially create a cooler microclimate during reproductive growth. Secondly, by ensuring adequate soil moisture during initiation of reproductive growth with proper irrigation, the crop may be able to withstand more heat and maintain adequate retention of pods and blooms. Here’s a chart from the 2012 UGA Soybean Production Guide concerning soybean water use.

Peanuts Being Dug

Peanut digging time is here. many fields are being flipped over today and drying and curing conditions for the vines and pods are pretty good however, we have had showers yesterday that stopped picking in some fields.  Also, the wind has been out of the east and with “the wind out of the east they will pick the least.”  Some final fungicide applications are going out on late planted fields but it’s pretty much done. The general rule is if you have good vines with no approaching long periods of rainy weather , then if peanuts are within 2 weeks of harvest, you are ok.  We have small vines this year and it is making digging a little tougher in dryland fields especially.  You need enough vine to get the inversion process going well.  Irrigation is not over for peanuts and some are being watered to get the dirt right in preparation for digging. Also peanuts need to be kept well watered until 120 days . After that we can back off on the watering but they don’t need to go into a stress, so they’ll need a little water along.

Digging 6 rows.

 

Wade Kirkland and JW Warriner are digging these Tiftguards down near the lake. They look really good and stems are holding well, although getting a little weak.

Peanuts getting a drink even though they are over 120 days it has been dry right in this area.

Ethan Fiveash has some good dryland peanuts here. He has dug the end rows and will soon dig the field.

 

No New Well Permits

The GA EPD announced that consideration of new applications for agricultural water withdrawal permits in a 24-county area of southwest Georgia will be suspended.  This applies to new applications for groundwater withdrawal from the Floridian aquifer, as well as applications for surface water pumping from streams and rivers in the Spring Creek, Ichawaynochaway Creek, Kinchafoonee-Muckalee Creek, and Lower Flint river sub-basins in the Flint River Basin.  The suspension also applies to applications to modify existing permits to increase withdrawals or increase the number of irrigated acres.  This suspension will be reviewed on an annual basis beginning November 2013.  This suspension does not apply to applications were in the possession of EPD as of yesterday, July 30.

Note that this suspension applies to the Floridian Aquifer.  Some farmers may still be able to drill into deeper aquifers.

Thanks to Ken Lewis, UGA Extension Ag PDC and Anita Tabb, NRCS for help with this post.

Ultra Late Soybeans – Water Critical

Ultra Late Soybeans are coming up and growing and are being planted now in a variety of ways.  No till drilled into undisturbed corn stubble in 7.5 inch rows, burned corn fields and drilled in 7.5 to 15 inch rows, twin row planters on 18 inch rows, Vacuum planters on 30 inch rows, etc.  Stands I’ve seen so far are mostly good. Growers are putting out about 210,000 seed per acre or so.

Watering is critical just before planting and afterwards. Partly due to the difficulty of getting all the seed in the ground properly in rough conditions, if we keep the ground wet we can get those seed up that are very shallow and keep crusting down by keeping  soil moist.  With these 99 degree days we have to keep the soil and seeds cool as well with irrigation.

No Till Drilled soybeans are coming up well here in 7.5 inch rows.

Grampa would say it looks trashy but it works.

Combine is in this in the field on the other side and the grain drill is here crisscrossing the field putting in soybeans. He’s using autosteer to make this easier.

 

No Till drill

Different field where they burned corn stubble and drilled 15 inch rows of Soybeans

Water

This is a better year than last year concerning rainfall.  Some of the cloudiness that came with rains may have affected corn yields, especially later planted corn. Corn needs lots of sunshine for top yields. 

Our local weather station at the Donalsonville Airport, www.georgiaweather.net , has recorded rainfall information available on the web for anyone to study. 

For all of 2012 we have received 26.41 inches here as compared to 21.98 inches in the same time frame in 2011. If you look at the long term average for our area we should get 31 inches. So we are about 4 ½ inches low for the year.  I believe that some parts of the county have gotten more rain than the airport and are actually above average in rainfall for this year. 

Let’s look at rainfall since we started planting corn.  If we look at accumulated rainfall from February 25 until July 15 for 2012 we have been blessed with 18.41 inches. Last year we got 13.92 inches during this time.  Our long term area average is 22 inches.  So we are about 3 inches low for the summer crop season.  

Another measure of how we are doing in regards to water is the water level in the Floridan aquifer under us.  In a nearby test well, it’s close to 46 feet down to the water.  If you look at a 31 year average it’s normally 35 feet down to the water level this time of year so we are about 11 feet low at this time.   

The worst we got this year was in February when our water level was 20 feet below average for that time of year.  It was at about the actual level it is now but we usually get winter recharge at that time, so the 31 year average is higher. Here is a graph showing the 31 year average in Gold and the Blue line is the level for the last year. 

I have links to the test well site under the blogroll section on the left side of the blog.

Spring Creek, below Brinson, last week was low but I’ve seen it lower, here we are canoeing down it last Saturday.

 

Corn Nearing End

Relatively new county agents from nearby counties, Andrew Sawyer, Thomas County and Max Demott , Mitchell County,  were here recently looking at some crops with me.  We found stink bugs, you can see the hatchout of young bugs and the adult brown stinkbug on the corn leaf.

We noticed that corn is in the early dent stage in many fields.  So it needs a couple more weeks or so until black layer formation when irrigation can be cut off. We need to keep it wet now, however as corn uses 3 tenths of an inch of water per day.   When fully dented , it will decrease to 0.27 inch per day. But we need to keep water on it until black layer formation. You can start to see the milk line go down from the top of the kernel as we go from dent to black layer.