Deep in-row subsoiling with the paraplow did provide a significant cotton yield increase in a totally different year in 2003 with a cool wet spring and high rainfall summer, which is just opposite of 2002. The 2003 subsoiled plots did provide a slight visual height advantage when compared to the replicated paraplowed plots subsoiled prior to 2003.
The late(headed) wheat small grain cover crop termination(burndown) did provide a slight yield increase over the early(tillering) kill in both cover crop tests. The stand counts and organic matter content was almost the same for the early verses the late killed cover crop. The adequate rainfall received throughout the growing season did not provide the “normal” conditions necessary for the late maturitity cover crop to show a significant annual yield advantage due to short term droughts.
An area comprehensive cotton survey with 68 fields in 2001 provided information revealing that 68% of the fields exhibited hard(traffic)pans and that the organic matter in the top 2 inches of the soil profile averaged less than .6%. The wholesale adoption of conservation tillage has magnified the need for education with practices favorable to growing cotton with regard to tillage and organic matter content. When small grain cover crops are utilized, they are typically terminated at the tillering stage which greatly eliminates the cover crop value in increasing organic matter and the mulch benefit.
The goal of the project is to successfully show with on farm commercial operations that proper tillage and utilization of small grain cover crops can provide a profitable long term sustainable cropping system . The success was measured objectively by stand counts(plants/row foot,skip index), organic matter content and most of all cotton yield with the improved tillage and covercrop management practices with conservation tillage.
The cotton tillage test consisted of replicated treatment areas in conservation tillage with treatment compared with deep in-row tillage performed in 2002 & 2003,2002 and prior to 2002. Pentrometer probing revealed hardpans in the unparatilled treatments. The success of the test was measured objectively with cotton lint yields.
The cover crop cotton tests were identified by identifying cotton fields that were planted in a small grain cover crop and exhibited an adequate stand of wheat. The test fields had a broadleaf herbicide(2,4-D) applied in February to selectively control the most damaging winter broadleaf weeds while retaining the small grain cover crop for more growth and development. Replicated strips of the wheat cover crop were terminated with an early burndown herbicide treatment in early March while tillering. The adjoining alternating strips were killed by a late burndown chemical treatment at the boot-head stage. Stand counts of cotton plants per row foot and skip index scores were taken approximately 60 days after planting to exhibit the competition for available moisture by the small grain cover crop at cotton planting. The value of the cover crop was measured by the organic matter in the top 2″ of the soil profile and the lint yields of the cotton for the early and late killed wheat cover crops.
The 2002 and 2003 crop years were very opposite, with 2002 being one of the dryest and 2003 being one of the wettest in many years. The lack of a normal two week drought during any of these years left the desired conditions to exhibit the value of the tillage and cover crop management practices.
The deep tillage test did show a significant cotton yield increase and also a favorable visual plant height advantage when compared to the unparatilled treatments in 2003.
Though we expect more response to deep tillage in a dry year, the 2003 deep tillage provided a 110 pound cotton lint/acre increase over the 2002 deep tillage and 120 pounds more cotton lint per acre over the tillage prior to 2002. This is probably due to increased internal soil drainage providing more oxygen and a favorable environment for the cotton to grow and develop. The low areas in the field that were paratilled showed a marked plant height advantage over the adjoining areas that did not have deep tillage applied in 2003.
The late kill verses early kill small grain cover crop tests exhibited a 40 and 13 pound yield advantage in cotton lint per acre . The stand counts for the late verses early kill are 1.74verses 1.88 plants/row foot and 1.61 verses 1.49 cotton plants per planted foot of row. The skip index was equal (.13) to only slightly inferrior(.13 verse .10) for the late verses the early cover crop kill, which is important as many farmers are afraid to kill cover crops late in maturitity fearing they will compete against the cotton seedlings for available moisture. The organic matter was the same for both the early and late kill cover crops. The desireable organic matter of 1.3-1.6% along with the adequate rainfall in both tests probably resulted more favorable conditions for both treatments that corresponded to very similar cotton lint yields.
Educational & Outreach Activities
The information from these tests were presented at the Central Alabama Cotton Workshop in January, 2004 and in a preplanting cotton newsletter to area cotton growers.
The tillage test had a significant bearing on the amount of deep conservation tillage
for the 2004 cotton crop. Very little deep tillage was performed in 2003 while almost all of the conservation tillage cotton has or will be deep tilled in the 3 county area in 2004.
More small grain cover crops has been planted and the management shown in these tests has been adopted by area cotton farmers.
The deep tillage grossed 69 more dollars per acre than the unparatilled treatments. The average yield advantage of 115 pounds of cotton lint valued at $.60 per pound with the cost of the deep tillage at $12/acre nets an average profit of $57/acre.
Employed over the 22,000 cotton acres in the 3 county area, it translates into 1.25 million dollars.
The late killed cover crop practice yielded an average of 26.5 pounds of lint cotton per acre which valued at $.60/lb should be worth $302,100 dollars for the 19,000 acres of conservation tillage in these Central Alabama cotton growing area.
The deep conservation tillage was adopted on almost all conservation acres for the 2004 cotton crop of about 19,000 acres.
Small grain cover crops are steady being more incorporated with the management for more utilization being employed by the practices exhibited in the cover crop tests.
Areas needing additional study
Refined cover crop management practices need more research and on farm teaching opportunities as it relates species selection, management and favorable economics of adaption that can be presented both with short and long term benefits in soil quality and crop yield.