AGRO 3503, Unit II-2.  Corn production: tillage, fertility, growth and development, water.

Notes, links and quiz. 


The objective of corn establishment is to get the crop planted as soon as safely possible.  In Arkansas, this is usually from late March to about early May.  The reasons for early planting are to avoid late season insect pests and droughts.  The main problems are wet and cool soils, which can delay planting and weaken seedling vigor.  Most corn growers plant in wide row spacings ranging from 30 to 38 inches.  Planting rate is determined from the hybrid variety recommendations and expected yields.  Seeding rates can be slightly adjusted upwards in fertile, well-drained soils that are irrigated.  About 80% of the corn planted in the mid-South is irrigated.  Corn responds well to irrigation and subsequently can have severe yield losses if drought stressed, especially from tasseling to soft dough stage.


Study the chapters from the Arkansas Corn Production Handbook (MP437) to answer the following questions. 



1. When planting, regardless of planter brand, corn yields decrease by about ___% when

    ground speed is increased from 4 to 7 mph.

            A. 10%                        B. 20%                        C. 30%                        D. 40%


2. ‘Ear-Flex’ refers to:

            A. ability of corn ears to increase in length and girth in low populations.

            B. ability of kernel to point upward if plant populations are too high.

            C. ability of corn plants to produce more ears in low populations.

            D. hybrids that have genetically set ear lengths and girths, regardless of population.


3. How many seeds per 10 ft of row would be dropped to achieve 28,000 seeds/acre

     in 36 in rows?

            A. about 19                    B. about 23                       C. about 16                    D. about 12


4. In Arkansas, higher yields are usually produced with hybrids having a maturity of about:

            A. 90-110 days                                         B. 105-112 days

            C. 112-120 days                                              D. 120-160 days


5. What are four reasons for planting corn as early as possible?






Drainage and Irrigation

1. Why is raised bed planting recommended for relatively flat soils?



2. Sedimentation problems in drainage ditches can be reduced by:

            A. planting no-till and reduced tillage

            B. planting early season hybrids

            C. delaying planting until May or June

            D. installing underground drainage pipes


3. In Arkansas, properly scheduled irrigated corn should yield:

            A. between 100 and 125 bu/acre             B. at least 175 bu/acre

            C. over 250 bu/acre                                          D. between 125 and 150 bu/acre


4. The most critical time to irrigate for high yields is:

            A. V1-V7                                                            B. tasseling to soft dough

            C. V7-V12                                                            D. soft dough to dent


5. In Arkansas, irrigation costs typically range:

            A. $2-$5/acre                                                 B. $3-$6.50/acre

            C. $5-$8.50/acre                                            D. $9.50-$12/acre



Fertilization and Liming

1. The recommended lower limit for soil pH before lime is needed is:

            A. 4.5                          B. 5.5                               C. 5.7                          D. 6.2


2. If corn yield goals are 200 bu/acre for a silt loam soil, how much N fertilizer

     is recommended?

            A. 100 lbs N/acre                                      B. 180 lbs N/acre

            C. 210 lbs N/acre                                      D. 240 lbs N/acre


3. In a typical nutrient uptake pattern for a corn crop in Arkansas, approximately

    75% of the K is taken up on about:

            A. May 1                                                            B. June 1

            C. July 15                                                            D. August 1


4. The micronutrient most likely to be deficient in Arkansas is:

            A. P                             B. Zn                                C. Fe               D. Cu


5. What type of soils are micronutrients most likely to be deficient in?