As we begin to evaluate the success of corn pollination during the 2012 drought, it might be useful to alsoevaluate which management decisions were most beneficial during this growing season. Although a season like 2012 is rare and extreme, it will likely happen again. Taking some time now to evaluate your management decisions might help during a future growing season.

Our last major drought year was 1988. There were numerous experiments established around the state by Dr. Paul Carter. Below I summarize his results for a number of management decisions that were important at the time including hybrid selection, plant density, date of planting, tillage and rotation decisions. Thequestionis, "How do these decisions affect grain yield during a drought growing season?"

Hybrid performance

Hybrid performance was lower than the previous 10-yr average at 8 of 11 locations (Table 1). No grain yield was harvested at Chippewa Falls. Three locations, Galesville, Hancock (irrigated) and New London, had greater yields than the average of the previous 10-years. All other locations had 18 to 51% lower yields with Lancaster significantly lower than normal. Harvest grain moisture averaged 18.7% to 24.7% among the trials. Plant lodging was less than 6% at all locations. At 9 of 11 locations, the maximum yielding hybrid was better than the 10-year average.

Table 1. 1988 Wisconsin Corn Performance TrialsSummary.
	1978-1987		1988		Percent	Max	Min
Location	N	Yield	N	Yield	change	Yield	Yield
Arlington	756	185	166	131	-29	175	84
Janesville	706	184	166	151	-18	186	104
Lancaster	706	146	166	71	-51	111	35
Fond du Lac	718	138	151	114	-17	151	71
Galesville	718	157	151	162	3	217	104
Hancock	719	170	151	198	16	236	166
Chippewa Falls	510	141	---	---	---	---	---
Marshfield	510	125	126	99	-21	127	58
New London/Waupaca	514	152	126	172	13	195	113
White Lake	54	135	58	94	-30	111	64
Spooner	534	115	116	87	-24	145	34
Yield= bushels per acre N= number of hybrids tested Percent change= the yield during 1988 compared to the average yield of the previous 10 years

Plant density

The plant density which produces maximum yield has been increasing over time, but what happens during a growing season with drought? During 1988, a plant density experiment was established at nine locations with target densities of 18,000; 24,000; 30,000 and 36,000 plants per acre. At 7 of 9 locations, grain yield either increased or was not affected as plant density increased (Table 2). At Lancaster, grain yield decreased 16 bu/A from low to high plant density, while at Spooner grain yield decreased 27 bu/A. So even during drought years when a response to plant density is not expected, higher plant densities were only detrimental at two locations. The best recommendation would be to manage for potential yield with higher plant density because the only risk for return on investment is minor seed costs.

Table 2. Grain yield (bu/A) of corn planted at target plant densities of 18000, 24000, 30000 and 36000 plants/A at various locations in Wisconsin during 1988.
	Actual Harvest Plant Density (plants/A)
Location	18100-20500	22500-24100	28600-29900	33300-36800	LSD(0.10)
	Grain yield (bushels/A)
Janesville	125	133	137	139	7
Lancaster	64	62	50	48	9
Fond du Lac	109	112	118	108	NS
Hancock	160	175	193	188	9
Galesville	133	163	172	174	9
Chippewa Falls	39	34	32	20	NS
Marshfield	88	87	89	85	NS
New London	109	112	118	108	NS
Spooner *	78	71	66	51	11
* At Spooner target plant density was lower and resulted in harvest densities of 15900, 18600, 22000, and 24500.

Date of planting

Earlier planting dates are typically recommended for avoiding drought growing conditions. However, during 1988 the planting dates of May 13 and May 18 were higher yielding than earlier planting dates (Table 3). Some of the better performance of later planting dates has to do with timing of when drought (heat and water stress) occurs during the life cycle of the corn plant. Another interaction is the distribution of rainfall during the growing season.

Table 3. Grain yield (bu/A) response to planting date during 1988 at Arlington, WI.
Experiment 1		Experiment 2
Planting date	Grain yield (bu/A)	Planting date	Grain yield (bu/A)
April 18	59	April 27	67
May 13	63	May 26	84
LSD(0.10)	NS	LSD(0.10)	8

Tillage

During the 1980s, no tillage was becoming popular as a management practice. Usually due to cool, wet soils corn often experience "slow growth syndrome" and yielded lower thanconventionallytilled fields. During 1988, there were no differences between no-till and conventional-till in six experiments conducted at Janesville and Arlington (Table 4).

Table 4. Corn grain yield (bu/A) response to tillage during 1988 at Arlington and Janesville, WI.
Location	Conventional tillage	No tillage	LSD(0.10)
Arlington-Experiment 1	62	64	NS
Arlington-Experiment 2	83	69	NS
Arlington-CS rotation	75	77	NS
Arlington-CSW rotation	70	72	NS
Janesville-Experiment 1	117	112	NS
Janesville-Experiment 2	117	109	NS

Rotation

Rotation is probably the easiest management decision we have available to get "free" yield. During drought (stress) years it is even more important. Rotated corn increased grain yield 16 to 36 bu/A (29 to 59%) over continuous corn grain yield.

Table 5. Corn grain yield (bu/A) response to crop rotation during 1988 at Arlington, WI.
Rotation	Grain yield (bu/A)
Continuous corn	61	56
Corn-Soybean	97	82
Corn-Soybean-Wheat	--	72
LSD(0.10)	16	15