The first 12 rows across the field at the Corn Illustrated hand-planted and nitrogen test plots near Edinburgh lie next to an overgrown hedge row, with some trees 20 to 30 feet tall or more. Fortuantely, those 12 rows are border, not part of the plot.
If you have any doubt about how much tree borders can zap yields, or if you've never had the opportunity to check such a thing on a combine yield monitor, all you need do is see corn growing in that first 12 rows on a hot afternoon, in the midst of a season where corn is getting far less rain than normal. The wilting was incredible,. And the further from the trees, the taller the corn, even though it was still rolling up leaves in response to hurting on moisture supply. In fact, the scene resembled one of those AT&T/Cingular 'more bars' TV commercials, where the bars get longer as you move one direction of another.
The actual plot begins on what would be row 14. One row was left blank as a border. By row 14, the effect appears gone. Corn was still unfurled and healthy, a night and day difference, even where the same hybrid was planted next to the first 12 rows. Tree experts say to expect as many roots underground as there is tree canopy aboveground. Obviously it was just more than shading in the morning affecting the first 12 rows. Tree roots were obviously sucking up moisture. There is gravel at three foot deep on this soil, so competition for water of a serious note produces serious results rather quickly.
Plans are to harvest those 12 rows separately this fall, hopefully in pairs, to show how the effect is greatest near the trees, but that there's still impact several rows out. In this field, the first 12 rows represented about 0.7 acres.
The question becomes obvious- would the farmer be better off creating a field border there, even in a cash-rented field? And if so, how wide should the border be? Perhaps information gathered this year in a dry season will help answer that question, at least help set parameters on the dry end of the spectrum.
Suppose it costs $200 to raise an acre of corn, besides land costs. With escalating fertilizer prices and higher seed prices for hybrids with traits, that's a very conservative figure, that would likely not allow adequate return to cover machinery depreciation and labor. Nevertheless, suppose the expense is $200.
Suppose yield is cut by one-fourth. If the expected yield is 160 bushel per acre at $3, now it's 120 at $3. The 120 at $3 scenario still leaves $160 for rent, labor, machinery and profit. Suppose yield is cut by half, which is highly likely based on observations to date. Then 80 bushels at $3 produces $240 per acre, leaving only $40 to pay rent, far under the actual rental rate in the area. Cash flow till be negative.
Finally, suppose yield on the first 12 rows is only one-fourth, or 40 bushels, which seemed within the realm of possibility based on conditions last week. Suddenly you've got $120 income when you've spent $200 or more for inputs alone, not counting rent, machinery depreciation, interest, etc.
Perhaps the first 12 rows would be best left to raccoons and deer? It's a question perhaps more farmers will be asking after results are obtained and posted for this demonstration once harvest arrives.