Corn, grown in about 25 parishes each year, is an extremely important crop to Louisiana. In 2005, about 340,000 acres were planted in the state with an average yield of 135 bushels per acre. Some corn yielded much better and some much worse, depending on the region of the state it was in.
Acreage has been declining since 2003 but should stabilize around 350,000 acres.
For the past couple of years, we have not had optimal conditions at planting, which has delayed planting of several thousand acres. That and high nitrogen costs have caused the acreage slump.
The majority of the state's corn is produced in northeast Louisiana. Yields, however, have been 147, 139 and 172 bushels per acre for the north, central and south sections of the state respectively. These yields come from the last two years of corn core block data. We will continue to evaluate yield trends in the future with the demonstrations statewide.
Several factors go into making a successful corn crop. Mother Nature by far is most important. Following Mother Nature in no particular order are hybrid selection, effective burndown, planting date and rate, fertilization and irrigation.
Hybrid selection is extremely important. This year, around 60 hybrids are available to Louisiana producers from several different companies. With that many hybrids to choose from, you need to separate them some way. My preference is selecting on the basis of yield stability — essentially consistent yields from regional trials through the estimation of variance components for the target region. The core block demonstrations conducted statewide and the commercial variety trials are important in evaluating hybrids/varieties across numerous environments.
The LSU AgCenter tests commercial hybrids annually and produces a recommended hybrid list. The list is available online at www.lsuagcenter.com. Go to the corn link and you will be able to find the report. You also can access Extension demonstration data under the corn link. This will allow you to see how a certain hybrid did across a number of environments and cultural practices.
Not selecting the correct hybrid can be a serious mistake in a year when maximum yields will have to be obtained to justify the input costs.
Regarding planting date, the LSU AgCenter recommends planting from Feb. 25 to March 20. From the Extension core block data, some consistent trends have developed by following this recommendation. When the corn core blocks were analyzed over the last two years (2004 and 2005), yields were reduced by 10 bushels per acre weekly when planting date went from the first to the third week of March.
Rick Mascagni, an agronomist with the AgCenter, has been researching seeding rate and twin rows versus single rows in northeast Louisiana. His research has been producing interesting results. Evaluating seeding rates at 25,000 30,000 35,000 and 40,000 seed to the acre, the highest yields were reported for 30,000 plants per acre. In Rick's research, there was not much difference between single-row yields and dual-row yields. There have been some success stories with the twin-row system, but at this juncture, we have not been able to find a significant yield increase in the dual-row system in Louisiana.
In Rick's fertilization work, yields increased slightly in a dual-row system as the nitrogen rate increased from 150 to 240 units per acre. The same was not consistent in the single-row system with yields leveling off after 180 units of N were applied. When the two row configurations were averaged together, yield response peaked between 180 and 210 units of nitrogen. This research supports the recommendation on nitrogen fertilization in that on soils capable of producing 150 bushels per acre or more, 160 to 240 units of N can be justified.
Irrigation definitely pays dividends. Corn needs an adequate water supply to maximize yield. During the growing season, corn will need between 18 and 22 inches of soil moisture. The critical period is when kernels begin filling. Moisture stress during this time can be very detrimental to yields.
Corn input costs will be very costly this year. With reduced commodity prices, yield maximization will be critical. Paying attention to input issues will aid in producing the best crop that you can.
David Y. Lanclos is the soybean, corn and grain sorghum specialist at LSU AgCenter. e-mail: firstname.lastname@example.org