As cotton planting quickly approaches, the Texas High Plains are still experiencing moderate drought conditions. According to the Texas Tech University West Texas Mesonet website, an average of 0.4″ of precipitation (rain and snow) has accumulated from 1-November, 2013 to today (13-March) across all monitoring sites. Higher accumulations were observed in areas south and east of Lubbock where significant snowfall occurred.
Although these areas are in better moisture condition than the Lubbock area, more precipitation is needed to achieve adequate soil moisture for planting and to replenish the soil profile. Furthermore, recent high winds have depleted shallow moisture as evident by the dusty conditions.
If a significant amount of precipitation does not occur prior to planting, pre-plant irrigation may need to be applied for stand establishment. If planting too early and cool temperatures are observed, as was the case in 2012, the possibility of “chilling injury” is greatly increased. Temperatures at 41⁰ F can damage or even kill seeds. Damage to seedlings from chilling injury can include aborted root tips and decreased vigor. If the root tips are damaged or aborted, the roots will not penetrate the soil to normal depths and “crow-footing” may be observed. This results in plants that cannot obtain adequate moisture and nutrients from deeper soil depths and lower yield potential.
Getting off to a good start is critical to a successful growing season and optimizing yields and profitability. In summary, planting high quality seed at recommended seeding rates to a firm, moist seed bed at 65⁰ F or better with a favorable five to seven day forecast will greatly increase chances for success. Furthermore, variety selection is highly crucial and is considered one of the most important decisions producers face annually.
To assist with this selection process, several variety trials are conducted by both Texas A&M AgriLife Research and Extension. Trials are conducted to compare production differences in genetics and technologies. Also, varietal differences in resistance to specific pathogens and soil-borne pests are determined at multiple locations across the region. Finally, we have included below some updated excerpts from previous “Focus” articles that address variety selections and result reports as well as pre-plant soil sampling for deep nitrate-nitrogen.
Variety Selection Process
Selecting productive cotton varieties is not an easy task especially in the Texas High Plains, an area where weather can literally “make or break” a crop. Producers need to do their homework by comparing several characteristics among many different varieties, and then keying these characteristics to typical growing conditions. We can’t control our growing environment from year to year, but we can select the varieties we plant based on desired attributes.
It is very important to select and plant varieties that fit specific fields on your operation. Don’t plant the farm to a single variety, and try relatively small acreages of new ones before extensive planting. Don’t forget to plant fields with disease or nematode history with the best varieties having greatest levels of resistance to those specific conditions.
Variety Testing Publications
If disease and nematode are not an issue, then producers should scrutinize all possible university trial data available to see how a variety has performed across a series of environments, and if possible, across years. It is best to consider multi-year and multi-site performance results if available. However, due to the rate of varietal release, some new varieties are made commercially available which have not undergone multi-year university testing.
Dr. Jane Dever has published the “Cotton Performance Tests in the Texas High Plains and Trans Pecos Areas of Texas 2013” report. This report contains data on many entries in several small plot trials. Small plot trials enable producers to observe results from a large number of entries at multiple locations. These trials are normally conducted under uniform, disease-free conditions, unless a test is specifically targeted toward a certain disease. Dr. Dever has included summaries over locations for some sets of trials.
This is an outstanding resource and provides much information on variety performance, including lint turnout, fiber quality, earliness, plant height, and storm resistance. Results from locations with Verticillium wilt, Root-knot nematode, and Bacterial blight are also available in this publication.
The Texas A&M AgriLife Extension and Plains Cotton Improvement Program, “2013 Systems Agronomic and Economic Evaluation of Cotton Varieties in the Texas High Plains” report will be available soon. In the meantime, we have made available on the Lubbock website, yield and HVI results tables from most 2013 AgirLife Extension large plot variety trial locations (Systems and RACE).
The final report will contain multiple locations of replicated cotton demonstrations conducted by Texas A&M AgriLife Extension personnel in producer-cooperator fields across the region. Since these trials are planted and harvested with producer-cooperator equipment, the number of entries per site is generally less than 15, and many times less than 10.
However, these trials reflect a wide range of cultural practices, locations, irrigation types, etc. Producers should look closely at location or site descriptions and compare management practices of cooperating producers to theirs to make informed variety decisions.
Deep Soil Sampling for Residual Nitrates
With high fertilizer prices, special emphasis is being placed on reminding producers about proper soil sampling and testing techniques. One of the most costly fertilizers is nitrogen (N). Nitrogen is important for producing protein in plants and crop demand is very much yield driven. Establishing a realistic yield goal is the first task. Producers shouldn’t take the attitude that cotton is like a grain crop. The more nitrogen applied when given high water doesn’t necessarily translate into higher yield.
Many times we can retain the fruit in a high water input field but not have time to mature that fruit. This results in a large number of pounds of lint, but can significantly reduce maturity because the late-set bolls do not have adequate time to mature. Excess N can aggravate the problem by delaying crop maturity, especially if poor maturity weather is encountered in September and October.
There is a fine line between obtaining an adequate yield and having good maturity in the crop, especially north of Lubbock. Excessive N can result in 1) Unwanted crop growth which in turn will require plant growth regulator (such as mepiquat chloride) application – especially on varieties that are inherently “growthy”, 2) Increased Verticillium wilt problems, 3) Increased aphid problems, and 4) More harvest aid challenges at the end of the season.
Over the last several years agronomists across the state working in cotton have surveyed residual N in the soil profile in producer fields. Results from several of these locations indicate considerable amounts of N that should be accounted for when determining how much N fertilizer to apply.
Soil sampling to a depth of 24″ is recommended especially following the two most recent years where well below average rainfall was observed and yields were lower than anticipated. Under “normal” conditions, in the High Plains region, many fields may encounter this deep N somewhat later in the season resulting in a surge of green at a time when we would like for the fields to become more N deficient. Based on research projects this is likely a contributing factor to lower micronaire in some fields in years with poor maturing conditions.
The basic formula for success is this:
- Determine the yield goal in bales per acre for the field based on irrigation capacity, varietal performance, early season profile moisture, etc.
- Multiply this yield goal times 50 pounds of N per bale of production.
- Deep sample for residual soil N down to the 18-24 inch depth.
- Submit the samples to a soil testing laboratory, fully recognizing the depth that the sample represents.
- Use the appropriate conversion factor based on the depth of sampling to convert the nitrate-N test results from the laboratory to pounds of N per acre IF the laboratory does not provide this service.
- Subtract the amount of residual N found from the N fertilizer needed based on the yield goal.
If high nitrate-N irrigation water is used, then additional steps must be made to compensate for N delivery during the growing season. Based on 10 ppm nitrate-N concentration in irrigation water, application of an acre-ft (12 acre-inches) during the growing season will result in about 27 pounds of N being simultaneously applied. Few High Plains wells will have nitrate-N concentrations of that magnitude. However, with high fertilizer prices, the water should be checked and credits made for this against overall N fertilizer application.
