As in past years, several PFI cooperators evaluated starters and other banded fertilizers in 1994. By now it should be no surprise that results were mixed. Even where these fertilizers increased crop yields, there was sometimes no clear economic advantage.
Doug Alert and Margaret Smith, Hampton, were among the ridge-tillers trying out the deep placement applicator shoe for the Buffalo planter. In soybeans, the fertilizer, placed two inches directly below the seed, increased yield 3.1 bushels, but the benefit was less than the cost of the 2-6-12 suspension fertilizer (Table 1). In the corn trial, Doug and Margaret compared placement below the seed, two inches to the side, and a no-starter check treatment (Table 3). Their soil tests very high in phosphorus and high in potassium. There was no observable yield difference among the three treatments. Don and Sharon Davidson, Grundy Center, also used the deep banding planter shoe in a soybean trial (Table 1). There was no significant effect on yield. Jeff and Gayle Olson, Mt. Pleasant, evaluated a planter band too, this one two inches to the side of the soybean seed and consisting of just potash fertilizer (Table 3). There was no yield effect. The potassium soil test there is between medium and high.
The usual method of deep banding involves a separate pass with an implement in the fall. Harlan and Sharon Grau, Newell, took this approach, comparing a fall deep band, fall broadcast, and a no-fertilizer check treatment. The corn in the deep band treatment yielded significantly better than the check treatment (nearly 16 bushels), with the broadcast treatment falling in between (Table 3). Soil tests are medium-to-very-high for phosphorus and high-to-very-high for potassium. Different results were obtained by Allen and Jackie Tibbs, Alden, who no-till planted soybeans directly over a fall band of fertilizer. They reported no yield increase from the fertilizer band (Table 1). The soil on this field tests low -to-medium for phosphorus and high for potassium.
Ron and Maria Rosmann, Harlan, have put their home farm in a transition to organic certification. They evaluated two rates of a mined rock phosphate on soybean yield, but saw no effect (Table 1). Their soil test for phosphorus was already medium-to-high.
Ray and Marj Stonecypher, Floyd, evaluated 3-18-18, a low-salt starter, which they placed right with the corn seed (Table 1). The 11 gallon per acre rate amounted to about 1+6+6 of nitrogen, phosphate, and potash. Surprisingly, leaf tissue tests showed a reduction in both nitrogen and magnesium where the starter had been applied. For the third year running, the Stonecyphers saw no yield effect from a low -salt starter. Their soil tests very high in P and K.
Probably the most ambitious starter trials in 1994 were carried out by Dick and Sharon Thompson, Boone, who evaluated both starters and timing of manure applications for corn and for soybeans (Table 2). How do you test both manure timing and starters in one trial? They used what is called a “split plot” design. The “main plots” represented different manure application times – fall (in the corn trial), spring, and a no-manure check plot. Each of these main plots was split into a subplot with starter fertilizer and one without starter, the location of each subtreatment being chosen at random.
In the Thompsons’ soybean trial neither manure nor starter affected yields measurably. However, in the corn trial, both manure and starter had an effect on yield. Fall applied manure was significantly better than the no-manure treatment, with spring- applied manure in between. The highest yielding treatment was fall-manure-plus-starter. However, because of spreading costs even this treatment lost money compared to the no-manure-no-starter treatment. Table 2 shows the economics calculated both for inyear costs and “prorated” spreading costs. Dick Thompson distributes spreading costs across all the crops of the five-year rotation, with each crop’s charge weighted according to its nutrient withdrawal. It’s worth noting that this field has been manured two or three years out of five for some time, so all treatment yields reflect the long-term benefits of manure. Soil tests for P and K are both very high here.