Angima, S.D., Assistant Professor- Extension, Oregon State University Extension
Steinhardt, G.C., Professor, Purdue University
Willoughby, G., Agronomist, Helena Chemical Company

ABSTRACT

Corn following corn often produces lower yields than corn following soybeans. However, differences in yield can be intensified when different planting practices, especially as a result of unintentional mistakes made by farmers (malpractices) play a role. Our objective was to evaluate the effect of these malpractices on final stand count, plant heights, and yield for no-till corn production on corn residue. Eight treatments and three replications were assigned in a randomized block design in 2000 (wet year) and 2001 (drier year). The treatments were: conventional tillage (CT), normal no till (NT), soil too wet and cold (TW), light pressure on press wheels (LPW), no starter (NS), double starter (DS), planting too shallow at one-inch depth (TS), and planting on compacted soil (CS). Planting too shallow resulted in less plants/acre especially in a drier year. Planting too early in wet-cold soils resulted in the shortest plants but these translated to substantially higher yields compared to other treatments. Planting too shallow was consistently the lowest yielding treatment in both years. Even though planting mistakes led to differences in yield, these yield penalties were minimal and may not be as big as commonly reported. In general, yields were more dependent on climatic conditions especially moisture, than planting practices. These results could be used by farmers and consultants to help predict potential yield losses and ensure that the worst planting mistakes are not routinely committed.

Introduction

Extension professionals give advice to farmers using university researched data. To develop appropriate research protocols, agents collect information from observations in the field, develop research criteria, and provide feedback to farmers and consultants. This research emulated this model by designing a research protocol based on unintentional mistakes made by farmers in planting no-till corn.

On moderately to poorly drained soils, crop rotation, type of residue, amount of residue and planting practices can be significant factors determining the performance of no-till corn production systems. Corn following corn often produces lower yields than corn following soybean (6). However, differences in yield can be intensified greatly when different planting practices, due to unintentional mistakes (herein called malpractices) play a role. Such yield differences can persist even when soil and drainage improvements are made (4,6). Malpractices may include placing seeds too shallow, little or no starter fertilizer, early planting in wet-cold soils, faulty or loose press wheels, and planting on compacted fields. These malpractices can affect emergence rates, early growth and health of corn plants, and yield.

Uneven seedling emergence can result from early planting, planting under reduced tillage, compacted soils, shallow planting, and planting in wet or cloddy soils (9,15). Other causes may include; soil crusting, herbicide injury, insect or disease damage, non-adjusted closing wheels, varying seed depth, different soil types within one field, and variation in topography (1,3). Compacted soils tend to reduce aeration and biotic activities which in turn contribute to reduced growth and vigor, resulting in less yield (7,8,10,16). Planting shallow may contribute to the rootless corn syndrome where corn is anchored in the soil by a single nodal root or by seminal roots (14).

Planting depth problems are associated with inadequate down pressure by the drill that creates poor seed-to-soil contact usually caused by sidewall compaction. Also coulters, running too deep than the double disc openers, may contribute to uneven seed depth. Finally, starter fertilizers can increase early-season growth and final grain yield (11,12), on soils with adequate P and K (2,14). Starter fertilizers are especially important in cool soils that occur with early planting in high-residue production systems where seedlings benefit from localized availability of P (5) and enrichment with N in the seedling root zone (3).

Our study was conducted to evaluate the effect on yield when common malpractices on planting corn are taken as limiting factors in no-till corn production on corn following corn. We investigated the effect of these factors on final stand count, crop development, and yield components. Understanding how these malpractices affect yield should aid in developing sets of criterion for gauging yield loss when other environmental factors are kept constant in no-till corn production systems.

Research Design

Studies were conducted in 2000 and 2001 on a moderately well drained Rockfield silt loam (Typic, Argiaqualf) located at the Purdue University Agronomy Research Farm in Indiana (40°, 28’,05’’N and 86°, 59’, 11’’W). The site was continuously cropped to alternating no-till corn and soybean for the last 17 years. The study consisted of corn (Becks 5402) planted in three blocks in a randomized block design of eight treatments and three replications for a total of 24 plots with each plot measuring 10 by 80 feet. The treatments were based on observed planting practices and malpractices for corn and were:

(i) conventional tillage (CT); (ii) normal no-till corn planting (NT); (iii) planting when soil is too wet and cold – on second week of April each year average air temperatures (TW); (iv) light pressure on press wheels (LPW); (v) no starter fertilizer (NS); (vi) double starter fertilizer (DS); (vii) planting depth too shallow (TS), and (viii) compacted soil surface (CS).

The TW treatments were planted on May 12, 2000 (wet year - Fig. 1) and April 13, 2001(dry year – Fig. 1) when soils were wet and cold (< 50^oF) for normal corn planting. The rest of the treatments were planted on May 23, 2000 and April 27, 2001. Target planting depth was two inches, and one inch for TS treatment. Other than the NS treatment, starter fertilizer 19-17-0 was applied to all treatments at the rate of 28 lb N/acre. Side-dressing with UAN was done at 8 weeks to all treatments.

Corn was planted at 30,000 seeds/acre on 30-inch wide row spacing. Precipitation was monitored at the Agronomy Research Center about half a mile from the study site. Data

were recorded on final stand count for corn plants, weekly plant heights until silking, and final crop yields (hand harvested) adjusted to 15.5% moisture content. All data were subject to analysis of variance using SAS (13). A Fisher’s protected LSD test procedure was used for mean separations at P<0.05.

Emergence Rates and Final Stand Count

The year 2000 was generally wet but 2001 was drier with respect to the growing season (Fig. 1). Final plant stand count for 2000 and 2001 are shown on Table 1. In 2000, CT, CS, and DS, had significantly higher stand counts than TS and TW. The TW treatment showed the lowest emergence rates and lowest final stand count (25,000 plants/acre) that were significantly lower than DS, NS, CS, and CT (Table 1). In 2000, continuous rain delayed planting until May 23^rd, and this may explain why planting too wet resulted in the lowest stand count. Although seeds were treated with fungicide, some seeds succumbed to early season fungal diseases such as Pythium or Fusarium (visual observation). Lower soil temperatures in no-till corn do not delay corn seed germination, but reduces the rate of emergence compared to conventional tillage (1). Outcomes from this study show how serious it is to plant early on corn residue if the weather continues to stay wet throughout the growing season. The other treatment with lower final stand count was TS with 26,000 plants/acre. Since seeds were planted at about one-inch depth, the rough micro-topographies from the corn residue might have further limited the planter from penetrating the soil. This is why residue cleaners are important in no-till systems.

Fig. 1. Long-term monthly rainfall average (30-year average) and rainfall amounts for 2000 and 2001 at Purdue agronomy research farm in West Lafayette, Indiana.

Table 1. Final plant stand count (x1000) for eight planting practices for no-till corn on corn residue in the study period 2000 and 2001 at West Lafayette, IN. Values represents averages for germinated corn seedlings three weeks after planting.

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	Final Stand Count
Planting Practice†	2000	2001
----------------------------		--------------------------
		x 1000/acre)
CT	32a‡	29a
CS	30ab	24ab
NS	30ab	26ab
NT	29abc	28ab
DS	32a	23b
TS	26bc	8c
TW	25c	30a
LPW	29abc	27ab
LSD	4	6.2

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†CT, conventional tillage; CS, compacted soil; NS, no starter; DS, double starter, NT,normal no-till; TS, too shallow; TW, too wet and cold soils; LPW, light on press wheels.

‡Within columns, means followed by the same letter are not significantly different at P =

0.05 by Fisher’s protected LSD.

In 2001, treatments exhibited different characteristics than in 2000 because of the dry weather conditions at planting (Fig. 1). The TS treatment had the lowest stand count of 8,000 plants/acre that were significantly lower than the rest of all the other treatments (Table 1). The CT and TW treatments had the highest final stand count significantly higher than the DS and TS treatments.

Placement of 19-17-0 starter fertilizer has been shown to have no effect on final stand count (11). In our study, using no starter or double starter had no significant effect on final stand count, however, planting depth did affect final stand count as seen from the TS treatment (Table 1). In 2001 when it was drier at planting, the TS treatment had 20,000 plants/acre less than NT treatment showing that it is one of the worst mistakes to make when planting no-till corn and the weather remains dry during the growing season. If we were able to predict in advance that it will be a drier year, it will be beneficial to go out earlier and plant in wet soils as these seedlings emerge and establish earlier as indicated by the TW treatment (Table 1).

Plant Heights

 

Corn height measurements were conducted to see if these planting practices limited the plant’s capacity to grow. Average heights of plants just before silking are shown on Table 2. Increased growth rates have been shown to translate to increased grain yield (12). In 2000, NT, and DS treatments had significantly taller plants than TS, NS, and TW treatments. The treatments with the shortest plants were NS and TW with heights significantly lower than the other planting practices. Therefore, planting while it is too wet or planting without starter fertilizer may limit the plant’s ability to develop and compete for light.

 

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