Starter fertilizer increased corn grain yield

Starter phosphorus (P) and zinc (Zn) fertilizer increased early-season growth, plant height, P concentration, and uptake of P and Zn in plant tissue, relative to the unfertilized control. In some cases, starter fertilizer reduced days to maturity and grain moisture content. The  largest responses were seen when corn was grown after canola compared to after soybean. The high rate of MAP significantly increased grain yield by 11.5 bu/ac (770 kg/ha).

Corn production in Manitoba in 2023 has nearly tripled to about 553,900 acres (224,163 ha) since 2010. As a result, corn crops may be planted on several different stubble types, including canola.  Corn is highly dependent on mycorrhizal fungi, while canola is non-mycorrhizal, which could have impacts on corn growth and nutrient uptake. Additionally, starter fertilizer effects have not been studied extensively on corn in Manitoba. The objectives of this study were to evaluate corn yield, growth, and nutrient uptake response to side-banded phosphorus (P) and zinc (Zn) fertilizers when corn follows canola or soybean.

Research was conducted at Carman in 2015 and 2016, Stephenfield in 2015, and Portage la Prairie, MB in 2016. However the Portage la Prairie site was lost due to flooding in 2016, leaving 3 site years of data. Potential sites were targeted toward fields with low to medium Olsen P soil tests. In the spring prior to seeding corn, Carman 2015 tested high with 19 ppm Olsen P levels at the 0-6 inch (0-15 cm) depth, while low testing sites included  Stephenfield 2015 at 6 ppm and Carman 2016 at 9 ppm.

Zinc levels ranged from 0.82 to 1.91 ppm DTPA soil test 0-6 inch (0-15 cm) depth. Only the Stephenfield 2015 site tested below the 1 ppm critical soil test threshold of Zn fertilizer application in corn.

Corn was seeded into a preceding crop of canola or soybean that had been tandem disced the previous fall. Sufficient nitrogen (N) was applied to all treatments to supply a target of 222 lbs N/ac (250 kg N/ha) accounting for soil residual and applied fertilizer N. Potassium (K) was applied as needed in the fall prior to tandem discing.

Four starter fertilizer treatments were applied in addition to a control with no starter fertilizer. Starter P treatments used two sources of monoammonium phosphate (MAP, 11–52–0) or MicroEssentials SZ (MESZn, 12–40–0–10– 1) side-banded 2 inches (5 cm) to the side and 1 inch (2.5 cm) below the seed) during corn planting in the spring. For the MAP treatments, additional ammonium sulphate fertilizer was applied to match the S rate in the MicroEssentials SZ treatments.

The treatments were:

T1:  Control (no starter fertilizer; no added S beyond basal treatment)

T2: 27 lbs P2O5 + 7 lbs S/ac (30 kg P2O5 + 7.5 kg S/ha) (MAP+AS)

T3: 53 lbs P2O5 + 13 lbs S/ac (60 kg P2O5 + 15 kg S/ha) (MAP+AS)

T4: 27 lbs P2O5 + 7 lbs S + 0.67 lbs Zn/ac (30 kg P2O5 + 7.5 kg S + 0.75 kg Zn/ha) (MESZn)

T5: 53 lbs P2O5 + 13 lbs S + 1.34 lbs Zn/ac (60 kg P2O5 + 15 kg S + 1.5 kg Zn/ha) (MESZn)

Arbuscular mycorrhizal fungi (AMF) colonization of corn roots was measured at the V4 stage from the control (T1) and the high rate of MESZn (T5) treatments. No significant differences were found in arbuscular hyphal or vesicular colonization of corn roots between corn grown on canola or soybean stubble at any site year. In the experiment, all fertilizer treatments had high rates of AMF colonization, and the addition of starter fertilizer reduced arbuscular colonization by only 6%.

Starter fertilizer improved crop growth and yield

Measured at the V4 corn stage, early-season biomass for corn grown after canola was much smaller than after soybean. On canola stubble, starter fertilizer increased early-season biomass by 85 to 111% compared to the unfertilized control. On soybean stubble, the response was much smaller with 3 sites having higher early-season biomass from 30 to 44% higher compared to the control (excluding the low rate of MESZn). Early-season biomass was similar for corn grown on both types of stubble for all starter fertilizer treatments.

All starter fertilizer treatments increased corn plant height measured at the V7 growth stage. Overall, starter fertilizer increased corn plant height by 11 inches (28 cm) when grown after canola, and 6.3 inches when grown after soybean. There were no significant differences in plant height between starter fertilizer treatments when excluding the control.

Averaged across all sites, starter fertilizer decreased time to silking by 2 to 7 days. Within each site year, all fertilizer treatments reached silking on the same day regardless of preceding crop.

Grain moisture content was lower with starter fertilizer treatments when corn followed canola. In this crop rotation, average grain moisture content was 2.1 to 2.7% lower in the starter fertilizer treatments than the unfertilized control. For corn after soybean, grain moisture was similar between the fertilized treatments and the control. Overall, there was no difference in grain moisture between the 4 fertilized treatments.

Corn yields were 3.4 bu/ac (231 kg/ha) higher after soybean than canola, but this was influenced by site-year. At Stephenfield 2015, corn after soybean yielded 10 bu/ac higher than after canola, but the other 2 site-years had similar yields regardless of stubble type.

There were no significant grain yield differences among the starter fertilizer treatments. However, when compared to the unfertilized control, only the high rate of MAP significantly increased grain yield by 11.5 bu/ac (770 kg/ha).

Overall, starter fertilizer increased early-season growth, plant height, P concentration, and uptake of P and Zn in plant tissue, relative to the unfertilized control. In some cases, starter fertilizer reduced days to maturity and grain moisture content, which could help reduce grain drying costs. The  largest responses to starter fertilizer were seen when corn was grown after canola. Grain yield response was smaller than early season growth responses, with only the high rate of MAP providing a significant yield increase to grain yield. The research found that the negative influence of the preceding canola crop on early-season corn growth and mid-season development could be corrected  with starter fertilization.

Financial support for this project was provided by the Manitoba Corn Growers Association (now Manitoba Crop Alliance), Canada-Manitoba Growing Forward 2 Program, Western Grains Research Foundation, Agrium (now Nutrien), Mosaic, and Western Economic Diversification Canada.

Magdalena Rogalsky, Kevin H.D. Tiessen, Don Flaten, Yvonne Lawley, Mario Tenuta, and John Heard. 2024. Response to side-banded phosphorus and zinc fertilizer for corn grown after canola or soybean in southern Manitoba. Canadian Journal of Soil Science. 104(1): 54-71.


Photo credit chas53

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