This is a question that we sometimes get regarding applications of biosolids.  Below is a table from the University of Missouri that was developed referencing EPA guidelines.  I think it is helpful information.  These levels are for soils with a pH of 6.5 or greater.  pH can have an effect on the availability of each individual metal.

Most heavy metals are reported as mg/kg on a laboratory analysis.  Mg/kg is basically the same as ppm.  So, for example, if your biosolids analysis reported a level of cadmium of 3 mg/kg that would be the same as 3 ppm.  You can compute that to being equal to .006 lbs/ton.  To reach the annual limit of .9 lb/acre for a soil of CEC 5-15 you could apply up to 150 tons per acre.  Most likely your application rates would be limited by other factors first, possibly other nutrient levels or economics.

The “Total” per acre limits in the table are the cumulative loading limits per acre or the amount that can be applied over a number of years of application.

Levels of heavy metals can be a concern, however, all soils have a certain amount of heavy metals naturally occurring in them. Yet, it is important to know the analysis of any biosolids you are applying so that you don’t misapply any minerals.  There are ceiling concentration levels for each heavy metal established by EPA that also limits applications of materials if they exceed these levels, but most biosolid materials fall within these parameters.

If you are a producer that just doesn’t want to risk applying unnecessary heavy metals to your farm then you should choose not to apply biosolids or wastewater products.

This year one of our customers applied PRO CAL 40 to the area of his field where the poorest soils (highest magnesium and clayey soils) were. He did not apply any PRO CAL 40 on the better soils (Kennebec).  Otherwise he treated the field the same.  As the picture shows below, the soils that he called the poorest appeared to be the best after the PRO CAL 40 was applied. This picture was taken June 1^st.

Picture 1.  Response from PRO CAL 40 application.  PRO CAL 40 was applied at 1 ton/acre on area to the left.

Below is a picture of the closeup of the plants.  The plant on the right from the treated area was darker green, larger, more girthy and had a larger root system.  Notice the yellow striping of the leaves of the plant which did not receive PRO CAL 40.  This striping could be caused by a deficiency of several nutrients, but in this case, it is most likely sulfur and zinc.  Zinc was applied in row in the starter which was applied across the whole field, but tissue tests showed that zinc levels were still deficient where no gypsum was applied.  Plant tissue tests revealed that the most significant increases in nutrients from the PRO CAL 40 application was zinc, sulfur and calcium, but also showed slight increases in nitrogen, potassium, and magnesium.  The increases in these were most likely a result of improved root growth and a healthier plant.

PRO CAL 40 does improve soil conditions and has a significant effect on root growth. Although we concentrate often on our most troublesome soils this shows that PRO CAL 40 can also benefit our better soils.

Picture 2. Comparison of plants where PRO CAL 40 was applied vs. no application.  Plant on right received 1 ton of PRO CAL 40 per acre.

Two recent articles on intensive soybean management research have similar themes and I thought would be worth sharing. One research article was from Better Crops magazine “Intensive  Soybean Management”…. Researcher was Gueillermo Balboa et al.  (Kansas State University) and the second article was in Corn and Soybean Digest “Understanding 120-bushel soybeans”….Researcher was Sotirios Archontoulis (Iowa State University).  You may want to check out these articles.  I will give my summation of both in this blog.

Water either by rainfall or by irrigation is critical to avoid limiting yield potential.  Canopy cooling may be an added benefit of irrigation under high daily temperatures. In the Kansas study irrigation accounted for 25 bushels over dryland or about 3.6 bushels per inch of additional water.  This is interesting since producers in Nebraska often comment that dryland yields are as good as irrigated.  Looking deeper into the Kansas study, the benefits of irrigation were not realized until rows were narrowed, plant populations were increased from 111,000 to 134,000 and N, P, K, S, Zn, Fe, B nutrients and fungicides/insecticides were included.  We must also consider diseases when increasing populations.  If you are in an area where white mold is of concern, narrowing rows and higher populations may create an environment more favorable for this disease.  The Iowa study also suggested narrowing rows and higher seeding rates along with earlier planting and longer maturity varieties can help realize better water and sunlight efficiency.

Although the Kansas study didn’t address planting date, the Iowa study stressed the importance of early planting to capture more sunlight for a higher yield potential. Nebraska research has shown that a soybean plant will put on one node every four days on average so with earlier planting there is potential for more nodes to set pods giving a higher yield potential.  Management for SDS should be a consideration when planting early if your field has a history.

Both studies stressed the importance of light interception……the more sunlight captured the more photosynthesis and, in theory, more food produced for either biomass or seed production.

The Kansas study showed a most interesting fact when comparing soybeans planted in 30” rows at 110,000 plants per acre and no fertilization or crop protection (common practice) to the soybeans planted in 15” rows at 134,000 plants per acre with fertilization and crop protection (intensive management). (Both were irrigated.) The “intensive management” soybeans had almost identical biomass at the R1 stage as the “common practice” soybeans.  Of importance, though, is that the “intensive management” soybeans accumulated 60% more biomass at the end of grain filling than the “common practice” soybeans. The ratio of seed to plant biomass was essentially identical, however, in both scenarios. For the “intensive management” soybeans more than 80% of the total plant biomass produced was accumulated during the reproductive stage. The Iowa study revealed the same….the higher yield was a result of greater biomass production.  As expected, N uptake patterns were similar to biomass accumulation.

On our farm in 2016 our earliest planted field revealed the same results with yields in the 75+ bushel range where populations were 135,000-145,000 plants per acre. In area of field where populations were less than 135,000 plants per acres the yield was less than 65 bushels per acre. This field did receive a foliar application of nutrients at the R2 stage.

Having adequate plant nutrition to produce a plant architecture early to sustain the demand on the plant during the reproductive stage is important. But balanced nutrition during the reproductive stage and having good nutrient release from organic matter later in the season is critical for producing plant biomass and high yields.  If nutrients aren’t sufficient to meet this demand supplementing with foliar applications should be considered.  Having a good environment for biological activity is important.  Eliminating as much stress as possible will also allow more energy produced by photosynthesis to be used for seed production.  Soil conditions were not addressed in either of these research papers but I know that soil is a factor in nutrient release, biological activity and in nitrogen fixation by nodules.

High yield production in any crop is a systems approach.  You can’t realize the benefits of one component if the others aren’t being addressed as well.  For example, earlier planting may not give you the added benefit if you don’t have adequate fertility or you don’t capture as much sunlight due to having wide rows.  In another example, foliar diseases can suppress the amount of sunlight captured which may reduce the early plant development.  This could reduce the amount of nodule development which could affect the amount of biomass produced later during the reproductive stages.  Sunlight interception and conversion of sunlight into energy most efficiently is paramount in all crops to raising our yield levels (of course with sufficient water.)

Call us at 712-433-0000 and discuss how we may be able to help you raise higher soybean yields.

In the fast paced world we live in today it is easy to forget to say thank you.  We don’t want to forget to say thanks to our PRO CAL 40 and NutraBio customers that had these products applied this past fall, winter or spring.  Soil Solutions feels very fortunate to have had a busy application season.   We started last September and finished the last week of April applying either or both PRO CAL 40 and NutraBio, with only a couple of short periods when field conditions did not allow us to spread.  There were a few fields that we were not able to spread due to being too wet.  We apologize to those customers and will make every effort to get them applied next season.

We say a special thank you to the retail dealers and advisors that handle our product. We prefer to work through retail dealers and advisors since they know their customers’ fields and have the relationship.  In areas where dealers don’t have the equipment to apply PRO CAL 40 or don’t want to apply PRO CAL 40, we help their customers by providing the service.

We also want to thank our truck drivers and trucking companies that helped us to get the product delivered timely.  They are asked to drive on icy and snow packed roads and start hours before sunrise.  Rodney Peasley is our trucking coordinator who works closely with our salespeople, our customers and our trucking companies to be certain that each day is scheduled and deliveries are made in a timely fashion.  It is stressful work especially when the weather changes as much as it has this year.  A big Thank You, Rodney.  Thank you to our applicator operators, Mike Freiderichs and Cameron Trudeau and especially to Ron Hanks.  Ron has been spreading PRO CAL 40 since we began in 2001 and there is not anyone better.  We receive numerous comments from our customers about the great job that Ron does.  Ron works long hours (sometimes not finishing until midnight and starting again at daybreak) to be sure that customers’ fields are done before the weather changes.  He applied to fields from Holstein, Iowa to Mound City, Missouri to Belleville, Kansas, all the way to North Platte, Nebraska and near South Dakota and everywhere in between.  His hard work is greatly appreciated!!

If you are a dealer who have customers who either haven’t had PRO CAL 40 applied or it has been a few years since they last applied, be sure to give Gene Kenkel a call. Gene has been our agronomic representative for over 10 years and works hard to bring agronomic knowledge to our customers, generate maps and directions for fields, and to be sure deliveries go smoothly.  We thank Gene for his dedication to Soil Solutions and our customers.

We also have office employees who help get maps ready, prepare work orders and all related billing. It really takes much more work than it may appear at first glance.  We appreciate their efforts to make it all go smooth.

Again, we say Thank You to our farmer customers who, without you, we would not be here to serve. We wish you all a very safe and profitable crop year.