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July 24, 1998 Vol. 98.10

IN THIS ISSUE:

Production:

SOIL TILTH

Most farmers when they feel their crops are not as good as they should be, automatically assume that the problem must be with the seed, the fertilizer, or the pesticides. However, experience has shown that, while these are obviously important factors, many times there are other more basic soil factors underlying the problems. Many of these can be categorized under the general heading of soil tilth. A soil with good tilth is mellow and friable and crumbles into granular soil aggregates. Soil tilth affects such things as water infiltration, water drainage, water holding capacity, soil aeration, ease of tillage, erosion potential, and root growth. All of these are critical factors for optimum crop production.

Management factors which influence soil tilth include tillage, compaction, and organic matter. Tillage, by definition, breaks down soil structure. The more a soil is tilled the more we break down the desirable granular aggregates that we associate with good tilth in a soil. Preserve soil tilth by minimizing tillage to that necessary to achieve a suitable seed bed. Also, avoid tilling wet soil and avoid repeated tillage with the same tool at the same depth.

Probably the most serious soil quality problem is soil compaction. Soil compaction occurs when heavy loads crush the soil structure and squeeze the pore space out of the soil. As the pore space is reduced, there is less capacity for the soil to hold the proper balance of air and water needed for optimum crop production. Compaction also significantly reduces root growth, which reduces the ability of the crop to get the water and nutrients that it needs. Because water acts as a lubricant between the soil particles, soils compact much easier when soils are wet. Compaction can be reduced by minimizing the load on the soil either by reducing equipment weight or by spreading the weight out with flotation tires, tandem wheels, etc. Also, avoid driving or working on wet soils. Manure spreading has been identified as a major cause of compaction because of large manure spreaders and the desire to get the manure spread before planting time when soils are wetter.

Soil organic matter is critical to soil tilth. Soil biological activity and organic matter provide the glues that cement soil particles into stable granular soil aggregates. Stable soil aggregates resist the breakdown of soil aggregates during tillage and when the soil is compacted. To have good soil tilth, soils must be managed to maintain or increase the soil organic matter level. To maintain organic matter levels, fresh organic matter must be constantly applied. The most common sources of organic matter are crop residues and animal manures and composts. Crop residues vary with the crop. For example, corn grain leaves a significant amount of crop residue on the field, however corn harvested for silage leaves very little organic matter. Cover crops grown as green manures can also add significant organic matter to the soil.

When looking to diagnose a crop production problem or looking for the next limiting factor to increased yields, don't automatically assume that it must be related to seed, fertilizer or pesticides. Look at the basic properties of the soil, in particular look at the soil tilth.

Douglas Beegle, Agronomy,
Soils

USING BY-PRODUCT MATERIALS AS SOIL AMENDMENTS FOR CROP PRODUCTION: A MATTER OF QUALITY

More and more industries and municipalities are attempting to find "beneficial uses" for their waste materials. The terms "by-product" or "residual" are frequently used to refer to waste materials that can be beneficially used. Economic factors are probably the major reason for the move to beneficially use by-products. Costs to dispose of wastes by landfilling or incineration keep going up, and many companies have discovered they can sell what they use to throw away. There are also good environmental reasons to reuse by-products. Beneficially using by-products allows us to reuse valuable resources, and decreases the amount of waste we need to dispose of.

Many by-products are being promoted as beneficial amendments for agricultural soils. Some of these are sewage sludge (biosolids), composts, food processing residuals, wood processing by-products, water treatment residuals, paper mill sludge, coal combustion by-products, lime and cement kiln dusts, and blast furnace slag. But how can we be sure that a by-product will benefit our soil and not turn our fields into disposal sites? To help answer that question we need to look at quality; the quality of the by-product, and the quality of the soil.

Any soil amendment will have both positive and negative effects on soil quality for crop production. This is true of by-products as well as products intended for use in agricultural soils. The decision of whether or not to use a particular amendment should be based on its overall effects on soil quality as well as on financial considerations. The following list of questions is intended as a guide in making that decision.

1. What characteristics of the by-product could potentially improve soil quality for crop production? These could include organic matter, crop nutrients, alkalinity, and gypsum. How consistent are these characteristics? Do the levels change?

2. What aspects of soil quality for crop production could be improved by using the by-product? These could include properties such as tilth, friability, water holding capacity, nutrient holding capacity, pH, fertility, cation exchange capacity, base status, and rooting depth. If the by-product will not improve any aspect of soil quality, then land application becomes disposal rather than beneficial use.

3. How much of the by-product would you need to apply to achieve the desired improvement in soil quality? Is this quantity of by-product going to be available when you need it? If not, can it be stockpiled? Do you have the equipment, capability, and time to transport and apply this much by-product. Is it feasible and practical to transport and apply this much material? If not, can the rate be adjusted up or down?

4. What aspects of soil quality for crop production would be deteriorated by using the by-product at the target rate? Both short-term effects (immediate onset but usually diminish with time) and long-term effects (gradual buildup but permanent) need to be considered. Short-term negative effects would include nutrient leaching or runoff, pathogens, soluble salts, soil compaction, anaerobic soil conditions, and excessively high pH. Long-term negative effects are usually due to the gradual build-up of trace elements in the soil from repeated applications of the by-product. Such buildup could result in reduced crop growth and yield, or introduction of unacceptably high levels of trace elements into the food chain.

5. Are there practical ways to manage application of the by-product that will minimize the negative effects on soil quality? This may mean lower application rates, fewer applications, limiting application to certain soil types or landscape positions, or not using the by-product at all.

6. Is the overall effect on soil quality positive or negative? Weigh those aspects of soil quality that will be improved against those that will be deteriorated.

7. Are there any regulatory, record keeping, or reporting requirements for land application of the by-product? If so, whose responsibility is it to follow them?

8. Is there a traditional soil amendment that can achieve the same soil quality benefit at less cost environmentally and economically?

Some by-products will clearly improve soil quality, while others could have more negative effects. Taking the time to find good answers to these questions from reliable sources will help you know the difference.

Rick Stehouwer, Agronomy
Environmental Soils

Precision Vision:

VARIABLE RATE APPLICATION - WHERE'S THE BEEF!

How many of you remember the television advertisement for Burger King back a few years ago, where the little old feisty lady holds up her fist and shouts, "Where's the beef!" Where Burger King was making a big deal about the size of their hamburgers, the media is now making a big splash about the great potentials of precision agriculture and all of the high technology tools that are needed to make the technology work for the farmer.

I have heard many of you during the past year in my travels around the state say to me, "this precision farming business just isn't for Pennsylvania, our farms are too small, the equipment is too expensive, it takes too much time, I have to learn computers" and on and on. These are legitimate concerns. Any farmer that is expected to make an investment of thousands of dollars must have convincing proof that there is a benefit to the investment. I think there is a need for potential users to question whether this whole thing of precision agriculture makes sense for the Pennsylvania farmer and producer.

On the other hand, I think that all of us who live in the present realize that there are only two directions to move, forwards and backwards. If there is no investment in learning and staying up with the competition, there is only movement backward. Precision farming is one of those new technologies that will impact the marketplace, and even farmers that want to keep production methods the same as always, must be aware that competition will increase. Although there are many variables that affect the profitability of a crop, the ability to more precisely apply nutrients does result in gross revenue. The question that still remains to be answered is whether the extra revenue in crop yield, justifies the extra investment in site specific (variable rate application) equipment. We will be talking more about the costs of precision application equipment in later articles. Here are some examples of farmers who were able to gain extra revenue from variable rate application.

Economic Benefit Examples:

(Taken from Site Specific Handbook, 5th ed., Ag-Chem Equipment Co. Inc, Minnetonka, Mn., 1997.) The benefits of site-specific farming can vary greatly by farming region, types of soil and crops grown. The following examples illustrate how areas and conditions can benefit from site-specific agriculture.

Corn - Minnesota

Potential added value associated with site-specific N rate management ranged from $4.45 to $29.15 per acre above conventional uniform rate recommendations. Corn was valued at $2.42/bu in 1994 and $3.64 in 1995. The ability to attain maximum profitability will depend upon accurate N rate predictions that are targeted to responsive and profitable areas of the field. (G.L. Malzer, P.J. Copeland, J.G. Davis, J.A. Lamb and P.C. Robert, Dept. of Soil Science, Univ. of Minnesota; and T.W. Bruulsema, Potash and Phosphate Institute of Canada, 1996)

Spring Wheat - Montana

Gross return for variable N fertilization was about $12 more per acre compared to uniform fertilization when nitrogen rate was based on tests from the top two feet of soil. The wheat was valued at $4.30/bu. (D.S. Long and G.R. Carlson, Northern Agricultural Research Center, Montana State Univ.; G.A. Nielsen, Dept. of Plant, Soil and Environmental Science, Montana State Univ.; and G.L. Lachapelle, Dept. of Geomatics Engineering, Univ. of Calgary, 1995)

Winter Wheat - Washington

Results based on field research indicate that variable fertilizer rates increased net returns over conventional management practices in Eastern Washington by $14.80 and $3.39 at two test sites in 1990, and $11.92 and $10.00 at two test sites in 1992. The wheat was valued at $3.50/bu. (TE. Fiez, B.C. Miller, and W.L. Pan, Dept. of Crop and Soil Sciences, Washington State Univ., 1994)

Corn - Kansas

Variable Rate Technology was shown to reduce the number of areas in the field that are either over - or under applied. The net return of Variable Rate Technology N management was positive at least once for each field during the two-year studies. The value of the corn ranged from $2.96 to $3.70/bu. (C. Snyder and T.Schroeder, Dept. of Agriculture Economics; J. Havlin, and G. Kluitenberg, Dept. of agronomy, Kansas State Univ., 1996)

Sugar Beets - Northwest Minnesota

Yields increased between 0.94 to 1.22 ton/acre, with recoverable sucrose content increasing between 0.44 and 0.47 percent. Recoverable sucrose increased by an average of 494-lb/acre. An average net return of $57.89/acre was realized. (A. Cattanach and D. Franzen, North Dakota State Univ.; and L. Smith, Univ. of Minnesota - Crookston, 1996)

Sugar Beets - Red River Valley, North Dakota and Minnesota

Few crops financially reward precision nitrogen management more than sugar beets. Yield and quality results show a Variable Rate Technology nitrogen management advantage over conventional single rate management. Net return per acre results are Univ. of MN (1994) at $75/ac, Univ. of MN (1995) at $48/ac, NDSU (1995) at $5l/acre and (1995) at $52/acre. (Dave Hilde, American Crystal, 1996)

Potatoes -Idaho

Returns to risk and management were $368.17/acre greater for a "precision ag" managed center irrigation pivot versus a "conventional" managed pivot. (Richard Johnson, Northwest Precision Ag Inc., Blackfoot, ID, 1997)

David Wagner,
Ag & Bio Engineering, Precision Ag


Agents Corner:


BERKS COUNTY

The first July heat wave started the week of July 20. Tomorrow's high will reach 98 degrees.

I noted the first corn to throw a flag leaf and show tassel last on Sunday, July 12. Since then, various fields have been in progression. I still see many uneven fields, some fields with late planting dates, or small sized corn that is just not developing. The unevenness cannot be blamed on any one thing. In my experience, there are combinations of causes.

Overall, good wheat yields are reported. The range I have heard is from 60 to 90 bushels per acre.

There were some diseased stands, but one grower told me it was his best crop ever.

Potato leafhopper damage is visible on some alfalfa stands. It seems to be worse on hot exposures (on shale) or on short stands.

In our statewide pasture measurement study, the rate of growth has slowed to "maintenance" (no gain/no loss). There have been generous showers, allowing an abundance of grass for intensive graziers and their cattle. (The exception is the west edge of the county.)

A nitrogen management tour was held in cooperation with the local conservation district and a fertilizer company in June. We are comparing 4 different treatments using manure and urea to meet yield goal. My one thought is that many agronomic basics still are learned by a producer that does plot work. I learn more from the farmer about his individual system, which I value highly.

Mena Hautau
Berks County

CRAWFORD/ERIE COUNTIES

When I last reported to you at the end of June, I commented that we were looking for some rain. Now, nearly a month later, we are still looking for that rain! Although some areas have been fortunate enough to receive some moderate but widely scattered showers, most areas have gone without moisture since the middle of May or over two months. Corn on coarser textured ground started to show signs of drought stress a couple weeks ago. Corn on our finer textured soils is showing stress now also. Much of the corn, especially the early-planted corn, is pushing tassels now. Even the corn that got planted mid-May and later (after the rains) is beginning to switch over to the reproductive stages. Much of that corn is short and under-developed. Obviously, adequate moisture for pollination is becoming critical. Our soil moisture reserves are nearing depletion. We are at a critical point with regard to weather making or breaking our corn crop. As I am writing this (Wednesday, July 22) hopes and anxiety are high. The forecast for today and tomorrow is for unsettled weather and rain as a large front moves through. Yesterday, most of the region received something less than an inch of rain. We all hope it will continue a while and be enough.

Another interesting observation regarding corn is quite noteworthy. I examined a field last week (mid-July) where Western corn rootworm adults were present in large numbers, on the order of 5 per plant. The field was planted mid-May and the corn was in the later vegetative stages. The rootworm beetles were feeding through the unfurled top leaves and completely devouring the succulent tassels. Both the very early presence of these adults and the degree of infestation were quite amazing.

With respect to forages, producers who were early on their first cutting generally got a pretty decent second cutting off as well. They are undoubtedly quite pleased as cool season forage production declined dramatically with the hot dry weather. Leafhoppers were generally reaching threshold levels as in second crop hay. The infestation appears to be fairly significant, but hopefully not as overwhelming as last years leaf hopper "plague." Many new seedings, both late-summer seedings from last year and this year's spring seedings have struggled due to the hot dry weather. Weed pressure has been a concern, but even the weeds have suffered. Generally, clipping has been a more popular and probably more prudent measure than herbicides.

Harvesting conditions for small grains were excellent. Yields and quality appear to have been better than normal. Of course, some of the later planted oats did not fair so well.

That's about it from the great Northwest. We're hanging on and hoping for some significant rains.

Joel Hunter
Crawford County

FAYETTE COUNTY

Annual crops, corn, oats, soybeans, wheat, are all progressing nicely. Ample rainfall during June and early July has resulted with everything still being "green" as opposed to "dried up". Wheat yields were variable, but still above average. Spring oats looks really good if adequate weed control was achieved. Weed free corn fields are looking strong and healthy with many fields producing double ears. Some corn fields that have low spots or poorly drained areas are expressing denitrification symptoms, some of which are very significant.

In FCN vol. 8, I presented a summary of the subsurface tillage trials conducted in 1996 and 1997. Additional trials were established this spring in a continuous corn field. On July 11, visual observations provided evidence the corn in the subsurface tilled plots was 4-5 inches taller than the conventional tilled plot. Interesting I thought.

Finally, first cutting hay is harvested, only about 35 days later than normal. Many dairymen have ensiled or baled second cutting and the regrowth has started again. Potato leafhopper damage has been sporadic unlike last year.

Pastures have begun to show the effects of overgrazing if not part of a rotational grazing system. Since the weekly accumulations of 1 inch or more of rain stopped, surface moisture limitations are becoming obvious.

Donald C. Fretts
Fayette County

LYCOMING COUNTY

Corn in the region is either fabulous or odd. Depending when it was planted and how much the fields were worked beforehand, there was a large influence on how well it germinated and how uniform it's growing. About one third is now tasseled. Uneven fields (of which there are many) will be raising havoc at harvest. The common opinion in this area is that it will be an "average yield" year. Recent thunderstorms have shown where early and heavy rootworm feeding has occurred. Scouting for adult beetles will start about 10-14 days earlier in the region.

Alfalfa is fair to good in most fields with limited moisture in areas slowing the growth of third cutting. Scattered storms have slowed harvest in many fields. Leafhopper damage is apparent in some fields with early harvest and insecticide solving the problem in others.

Small grains production is good this year with wheat harvest nearing completion with strong yields. Oats are ripening and nearly ready for harvest. Straw quality is good this year except for late-planted oats where it is shorter than normal. Weed control this season has been generally good with many of the post-emergence products being applied. Roundup-Ready fields looked rough early but are looking good now. I have made more post-recommendations than normal, which I believe, was due to both wider acceptance of these products and the conditions this spring.

Tom Murphy
Lycoming County

MIFFLIN/JUNIATA/PERRY COUNTIES

Warm temperatures are causing excellent growth rates for crops, weeds and insect pests. Most of the early-planted corn is showing tassels at a slightly shorter height than normal. Corn borers are active, causing stalks to break off in one field I looked at. Also, the Western Corn Rootworm beetles are starting to fly. The corn pollination should be acceptable if our current moisture conditions persist.

Wheat and barley harvest is finished with the oats harvest just beginning. Wheat test weights were in the 56 to 60 pound range. The oats quality looks good on the stalk, hopefully weather conditions will allow for a timely harvest.

Most of the second cutting alfalfa is harvested. Scattered rain showers lowered the average quality of hay made for this cutting. Potato leafhoppers are present in our area, but I have not had many reports of high numbers in established stands. However, new seedings continue to have higher leafhopper pressure.

Weeds in general seem to be more persistent in the grain crops this year. Local custom applicators are still getting calls for rescue treatments. They are struggling to keep inventories low and at the same time meet their customer's weed control needs.

Greg Hostetter
Juniata County

YORK COUNTY

Reports I've heard on wheat harvest are good (50-60 bu) and an occasional very good (70-80). Test weights were trying to grasp for 60 lbs. We got a 3" rain on July 8. Most of the wheat was harvested by then. Corn was just beginning to tassel so the timing was good. We do need rain again now since it has not rained since then and have had 90+ degree temps. Oats harvest is going on now. We had some feeding activity by green clover worm on some soybeans; first I am aware of in 13 years. Some growers were applying insecticides, according to one crop supply dealer in the area. A field I looked at would have justified control based on leaf damage, but for some reason the insect population crashed and no further damage was anticipated.

Another interesting page written in the strange chapter of this year's book.

John Rowehl
York County

Degree Day Accumulations:

1998 DEGREE DAY ACCUMULATIONS

To track corn and insect development, compare the 1998 cumulative degree-days shown in Table 1 to the required values in Tables 2 and 3. Choose a location that is closest to your site when making a comparison.

Table 4. Cumulative Degree Days for Corn and Insects for the Period Ending July 20, 1998
Corn Insects
County Location 1998 30-year ave. SCM/SB AW BCW CRW ECB
50F 50F Diff 40F 48F 50F 53F 55F
Erie Waterford 1255 1103 152 2479 1585 1384 1109 942
Crawford Meadville 1331 1180 151 2604 1682 1477 1194 1022
Mercer Mercer 1332 1177 154 2621 1689 1483 1199 1026
Bradford Towanda 1321 1191 130 2610 1678 1473 1188 1015
Lycoming Montoursville 1400 1269 132 2755 1785 1574 1280 1101
Tioga Mansfield 1243 1106 137 2482 1580 1378 1102 934
Susquehanna Montrose 1140 1005 135 2340 1461 1264 995 835
Butler Butler 1401 1249 152 2747 1784 1572 1279 1101
Indiana Indiana 1385 1235 149 2738 1772 1559 1266 1088
Lawrence Lawrence Jct 1345 1195 149 2613 1693 1489 1206 1033
Blair Martinsburg 1331 1181 150 2672 1715 1503 1213 1037
Centre State College 1332 1188 143 2654 1705 1496 1208 1033
Columbia Bloomsburg 1415 1284 131 2795 1810 1597 1301 1119
Clearfield Curwensville 1324 1178 146 2630 1690 1482 1196 1023
Dauphin Elizabethville 1456 1321 135 2880 1871 1654 1351 1166
Bedford Bedford 1421 1272 149 2829 1835 1617 1316 1133
Mifflin Belleville 1414 1273 140 2798 1813 1599 1302 1120
Northumberland Sunbury 1464 1331 133 2879 1874 1658 1356 1171
Lehigh Trexlertown 1482 1352 129 2938 1910 1690 1384 1195
Schuylkill Hegins 1408 1275 133 2799 1809 1595 1298 1116
Westmoreland Greensburg 1383 1229 154 2744 1776 1562 1268 1089
Somerset Somerset 1207 1041 167 2487 1566 1360 1079 912
Washington Washington 1464 1306 158 2876 1879 1660 1357 1173
Franklin Chambersburg 1516 1373 143 3004 1963 1739 1427 1236
York York 1558 1421 137 3090 2023 1796 1478 1283
Lancaster Ephrata 1475 1341 134 2940 1910 1689 1381 1193
Berks Hamburg 1499 1368 131 2963 1930 1710 1402 1213
Corn degree-days based on a May 1 starting date. Insect degree-days based on a January 1 starting date.


Table 2. Cumulative Degree-Days Required for Insects to Reach key Periods for Scouting or Management
  Maturity rating (days)
80 90 100 110 120
50% Silking 1100 1150 1250 1300 1400
Black Layer Formation 1900 2100 2300 2500 2800


Table 3. Cumulative Degree-Days Required for Insects to Reach key Periods for Scouting or Management
  Stalk Borer Alfalfa Weevil Black Cutworm* Corn Rootworm European Corn Borer Seed Corn Maggot
Adlt Emrg 5% Hatch 1st Gen 2nd Gen
SB AW BCW CRW ECB1 ECB2  
Initiation 1400 300 91 1283 380 WCRW** 558 1550 450***
Termination 1700 500 430 2253 478 NCRW** 1228 2045  

*Degree-day accumulation should begin at first moth capture in a black light or pheromone trap.
**These values represent degree day accumulations for optimal timing of Furadan 4F post emergence applications. WCRW-Western Corn Rootworm, NCRW-Northern Corn Rootworm
***This number of degree days represents the number of degree days required from plowdown of green vegetation until it is safe to plant corn or soybeans and avoid seed corn maggot injury.

Dennis Calvin, Entomology

William S. Curran
Associate Professor Weed Science
email: wsc2@psu.edu

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