Commodities: Fieldcrops: Peanuts
2009 Peanut Update
TILLAGE AND ROW PATTERN UPDATE
R. Scott Tubbs and John P. Beasley, Jr.
Tillage
There are advantages and disadvantages to using conventional tillage in peanuts, and the same can be said for strip-till in peanuts. Some benefits that can be gained from turning the soil include physical weed control of emerged seedlings, incorporation of PRE yellow herbicides for supplemental control of weeds, warming the seedbed for quicker crop germination, and so on. However, there are negative impacts like soil erosion, new weed seed brought to the soil surface, and rapid drying of the soil. With strip-till, cover crop residues remain on the surface, which serve as a mulch to shade weeds and slow the evaporation of water from the soil. In addition, conventional tillage can be costly in comparison to strip-till because of increased energy and time demands to pull implements through the field. If the same yields and grades can be achieved with fewer inputs, then the producer and sustainability of the environment will both benefit.
There is not a universal recommendation regarding which tillage system works best, and what works in one field or one year may not work in a different field or in a different year. That is why it is important to take more than simply yield alone into consideration when determining which tillage practice to adopt. In years with adequate rainfall, there is usually no difference in yields between conventional and strip-till. However, in dry years, strip-till peanuts will often yield more than conventionally grown peanuts. This is primarily with respect to the slower evaporation of soil moisture thanks to the presence of the cover crop. There is not always more available soil moisture in strip-till than in conventional tillage, though. Cover crops, especially when there is abundant biomass, may use most of the available water, leaving the soil dry prior to planting. Timing the termination of cover crops with planting of peanuts is important and may vary from grower to grower depending on how much residue can be managed without interference of the planting operation.
Also, diseases should be factored into the decision. Tomato spotted wilt virus (TSWV) and leaf spot incidence are both increased in conventional tillage management, while limb rot is increased in strip-till management. If planting a peanut variety that is more susceptible to one of these diseases, the type of tillage system utilized may need to be altered to lessen the risk of a severe disease occurrence. The impact of TSWV has been low on peanuts the last few years. Yet, since there is presently no in-season control for TSWV, growers should take every precaution to minimize the possibility of TSWV incidence.
A comparison of tillage, varieties, and row patterns has been evaluated on the UGA Tifton campus to study the effects of long term conventional and reduced tillage on crops. Data comparing the tillage effects on yield and TSWV are summarized in Fig. 1 and Tables 1-2 below for the 2005-2008 growing seasons.
- Differences among varieties within a given tillage are indicated by alphabetical notation, where a different letter indicates a statistical difference.
- Differences between tillage systems within a given variety are indicated by error bars (least significant differences), where bars that do not overlap indicate a statistical difference.
Table 1. Yield comparison of tillage methods, 2005-2007 – RDC Pivot, Tifton, GA.
Tillage Method |
2005 |
2006 |
2007 |
----------Yield (lb/ac)---------- |
|||
Conventional |
4695 a |
4494 b |
5765 a |
Strip-Till |
4507 a |
5355 a |
4943 b |
LSD |
218 |
295 |
162 |
Table 2. Incidence of tomato spotted wilt in peanut for two tillage methods, 2005-2008 – RDC Pivot, Tifton, GA.
Tillage Method |
2005 |
2007 |
2008 |
---- % TSWV incidence ---- |
|||
Conventional |
9.1 a |
6.6 a |
10.0 a |
Strip-Till |
9.7 a |
5.7 a |
9.7 a |
LSD |
2.2 |
1.2 |
2.9 |
In 2008, there was an interaction between tillage and variety. Four of the ten varieties (‘AP-4’, ‘Florida-07’, ‘Tifguard’, and ‘Georgia-07W’) had a significant difference in yield between tillage systems, with conventional tillage having higher yields than strip-till (Fig. 1). The remaining six varieties had no statistical difference in yield. Likewise, conventional tillage had higher yields than strip-till in 2007. Yet, in 2006 there were higher yields in strip-till and in 2005, there was no difference between tillage systems for yield (Table 1). No differences in TSWV were observed between tillage systems in any year (Table 2). It is believed that low levels of TSWV in 2007 and 2008 coupled with the inclusion of newer, highly TSWV resistant varieties in those years may be resulting in a yield emphasis for conventional tillage, diluting the impact that strip-till has on reducing TSWV in more susceptible varieties. If TSWV severity were increased, it is anticipated that TSWV incidence would increase in conventional tillage plots and be reduced in strip-tillage, causing yields to be inversely impacted, respectively.
Row Pattern
Like with tillage, there is more to take into account than just yield when deciding on row pattern. A study in Plains in 2008 which compared row patterns and seeding rates among seven varieties had higher yields (5504 lb/ac – twin; 5020 lb/ac – single) and lower TSWV (4.2% – twin; 7.9% – single) in twin rows than in single rows (for more information on that experiment, see the article “Update on Seeding Rates for Peanut” within this publication). The most recent data on row pattern from Tifton Campus has consistently shown no differences in yield between single and twin row patterns (Table 3). However, there were significant differences in TSWV in 2005 and 2008 (Table 4), favoring twin rows. Even though those differences were not enough to cause a reduction in yield in this study, it could be a significant factor with cultivars that are more susceptible to TSWV, or in years where heavy disease pressure hits the crop. Twin row patterns have also demonstrated the ability to reduce white mold since there is greater spacing between individual plants, slowing the spread of the disease. There are 3 seed per foot per twin row at planting compared to 6 seed per foot in a single row (same plant population regardless of row pattern, but plants have more space between adjacent plants in twin rows).
Table 3. Yield comparison of row patterns, 2005-2008 – RDC Pivot, Tifton, GA.
Row Pattern |
2005 |
2006 |
2007 |
2008 |
----------------Yield (lb/ac)---------------- |
||||
Single |
4679 a |
4939 a |
5284 a |
5402 a |
Twin |
4524 a |
4911 a |
5423 a |
5419 a |
LSD |
218 |
295 |
162 |
110 |
Table 4. Incidence of tomato spotted wilt in peanut for two row patterns, 2005-2008 – RDC Pivot, Tifton, GA.
Row Pattern |
2005 |
2007 |
2008 |
---- % TSWV incidence ---- |
|||
Single |
10.8 b |
6.7 a |
11.7 b |
Twin |
8.0 a |
5.6 a |
8.0 a |
LSD |
2.2 |
1.2 |
1.4 |
Therefore, because of the potential to reduce pest problems, which can lead to yield increases, twin row patterns are recommended by the University of Georgia for peanut production.