Demonstration of Corn Intercropping Systems to Improve Corn Forage Quality

Trial Site: Fairview Research Farm

Research Coordinator: Dr. Akim Omokanye

From: Peace Country Beef & Forage Association 2016 Annual Report

Over 100 corn forage samples have been analyzed for quality by PCBFA in the last few years, and the majority of the samples came from producers’ fields. In summary, the forage quality results have shown that corn would normally have adequate protein and energy values needed by gestating cows. Essential minerals (except for Na) are always being met as well by corn forage. Occasionally, the protein content may fall short of what is needed by cows at the late-pregnancy stage and for producers wanting to use corn silage for back-grounding calves, the 12-13% protein required by these calves can hardly be met by a sole corn crop. To address this issue, we decided to test a few different crop types with corn as companion crops in order to determine biomass yield and silage quality of corn mixed with other crop types. Studies elsewhere have shown that intercropping of corn with legumes is an alternative to corn mono-cropping and has a number of ad-vantages, for example, lower levels of inputs, lower cost of production and better silage quality than mono-crop systems.


The demonstration site was at the Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview. Soil test at 0-6” soil depth prior to seeding showed an organic matter content of 7.3%, a pH of 5.4 (acidic) and an electrical conductivity of 0.58 dS/m.

The field was cultivated before seeding corn.

Rainfall from seeding-killing frost was 13.8”. The date of killing frost was September 4 and the total corn heat units (seeding-Killing frost) recorded was 1711.

Demonstration strip design was used in small plots measuring 11.04 m2 (118.8 ft2).

Treatments (Varieties): A corn mono-crop (check) was tested against the following corn intercrops:

1. Corn/crimson clover (CC) broadcast (C-CCB) - CC was broadcast onto corn plot after corn spraying @ 4-6 leaf stage with Roundup Weather Max

2. Corn/CC intercrop (C-CCD)- CC was drilled between corn rows after corn spraying @ 4-6 leaf stage with Roundup

3. Corn/Tillage radish (TR) intercrop (C-TR) - TR was drilled between corn rows after corn spraying @ 4-6 leaf stage with Roundup

4. Corn/Hairy vetch (HV) intercrop (C-HVD)- HV was drilled between corn rows after corn spraying @ 4-6 leaf stage with Roundup

5. Same day seeding of Corn/Hairy vetch (HV) intercrop & sprayed with Roundup Weather Max (C-HVD-RR) - HV and corn seeded in alternate rows same day and later sprayed with Roundup when corn was @ 4-6 leaf stage

6. Same day seeding of Corn/Hairy vetch (HV) intercrop and sprayed with Basagran Forte (C-HVD-BF) HV and corn seed-ed in alternate rows same day and later sprayed with Basagran Forte when corn was @ 4-6 leaf stage

7. Corn/soybean intercrop (C-SOY) - same day seeding of both corn & soybean, followed by spraying of both crops with Roundup when corn was @ 4-6 leaf stage

Seeding rates:

1. Corn - 30,000 kernels per acre

2. Crimson clover broadcast - 4.0 lbs/acre, drill - 3.0 lbs/acre

3. Tillage radish - 2.0 lbs/acre

4. Hairy vetch - 3.75 lbs/acre

5. Soybeans - 70,802 seeds/acre

Corn as well as same day intercropping treatments were seeded on May 17, 2016. We used a 6-row John Deere corn planter at 30” row spacing. Fertility (lbs actual/acre) was 84 N + 30 P + 66 K + 0 S and broadcast just before the land was tilled.

Results & Discussion

Forage Yield

Most intercrops appeared to have some influence on total forage yield. Forage yield was much higher (5.9 tons/acre or more) for soybeans (C-SOY), hairy vetch seeded after corn spraying (C-HVD) and same day seeding of corn/hairy vetch & sprayed with Basagran Forte (C-HVD-BF) than check (mono-crop corn). The total forage yield as percent of check (mono-crop corn) varied from 98% for (C-CCB) to 127% for (C-SOY). The following intercrops did not seem to have any forage yield improvement over check (sole corn): C-CCB and C-HVD-RR.

We observed that corn height, corn cob development and corn forage yield were negatively affected by corn-tillage radish inter-crop system (C-TR). Tillage radish significantly reduced corn height compared to check and other intercrops. This is probably because tillage radish is known to take up N from both topsoil and from deeper soil layers, storing the N in their shoot and root biomass. Studies elsewhere have shown that more than 100 lbs/acre of N has been reported to be taken up by tillage radish from both layers, though it releases the N in spring. Tillage radish root dry matter has also been reported to commonly contain more than 0.5% P and 4% K.

It has been reported that Roundup is not effective in killing hairy vetch, so we decided to test that theory by seeding corn and hairy vetch same day (C-HVD-RR) and this was later sprayed with Roundup. We observed that Roundup did affect hairy vetch greatly, though it did not completely kill hairy vetch stands. Hairy vetch did recover slowly and the forage yield from Roundup sprayed hairy vetch plot was far lower than C-HVD-BF treatment, which was sprayed with Basagran Forte (Table 1).

Protein (Table 1)

Using tillage radish, crimson clover (when drilled), soybeans and hairy vetch as companion crops appeared to have improved forage crude protein (CP) content of the respective intercrops (12-14% CP) compared to check (11% CP). Overall, the CP exceeded the protein requirements of mature beef cattle and, in some cases, were well within the 12-14% CP needed by growing and finishing calves.


The forage energy (TDN) content of the intercrops (except for corn-tillage intercrop) as well as check was 67% TDN or higher (Table 1). The Corn + drilled hairy vetch (sprayed with Basagran Forte, C-HVD-BF) had the highest TDN (73%). Overall, except for corn-tillage intercrop, all intercrops and check had enough TDN for mature beef cattle, and were well within the 65-70% TDN required by growing and finishing calves. The C-HVD-BF intercrop system however, far exceeded the required energy for young and mature beef cattle.


The forage Ca, K, Mg, Na and S values were higher for Corn + drilled tillage radish (C-TR) than other intercrops and check (Table 1). The forage P content was higher for both C-TR and C-HVD-BF than other intercrops and check.

All intercrops as well as check met the Ca, P, K and Mg requirements of a dry gestating cow, but a few ( C-CCB and C-HVD-RR) fell slightly short of meeting the 0.15% S required by this category of cows. Corn + drilled tillage radish (C-TR) had far more Na content than other intercrops and check. The requirement of Na by a mature beef cow was exceeded by up to 0.21% by C-TR. The C-CCD system was within the recommended 0.06-0.10% Na for a mature cow.

The requirements of Ca & P (in some cases), K, Mg and S (except for C-CCB and C-HVD-RR) by mature beef cattle have all been met by these intercrops and check.


Except in a few instances, our observations from this demonstration of corn intercrops seem to show that drilling crops such crimson clover, tillage radish, hairy vetch and soybeans in alternate rows with corn may have the potential of improving both total forage yield and quality for the benefit of mature and young beef cattle. Intercropping corn with legumes such as C-SOY and C-HVD-BF, to some extent appeared to be more

effective than mono-crop corn in producing higher DM yield for silage with better quality. Successfully incorporating cover crops into silage corn production will take advanced planning to realize the benefits these crops can offer.

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