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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Winter 1995 Summary: Multi-year studies have shown that crops respond more favor- ably to starter applications in a reduced tillage environment than in conven- tional systems. Crop yields are im- proved. Yield losses resulting from de- layed planting are reduced. Fine tuning to achieve optimum efficiency in such a system involves 1) proper fertilizer rates, 2) proper placement, 3) proper hybrid selection, 4) proper fertilizer source, and 5) minimal leaching The fundamentals of a good management program cannot be overlooked. tudies throughout the country have shown a marked increase in starter response with tillage re- duction, regardless of soil test levels. The theory behind the starter concept is simple, but putting it into practice is not always easy. The idea is to get a concentrated band of nutrients near the seed at planting time. Concentration in- sulates the nutrients from tie-up by soil and biological activities. Placing nutri- ents close to the seed increases the chance for early uptake by seedlings. The myriad of equipment available is a testimony to the challenge. Usually a knife and coulter delivers liquid fertil- izer near the seed. Placement two inches beside and two inches below the seed puts the starter close enough to the seed to allow easy access by emerging seed- lings and yet far enough away to pro- vide an insulating barrier against un- wanted salt effects. The switch to no-till and ridge-till has placed some constraints on starter equipment. Some ridge-till planters have so much "iron" on them already that there is simply little room for another attachment. This and other reasons have revived interest in seed placement. Starter is ordinarily used to power the plant out of the ground and provide a boost until the crop reaches its grand vegetative growth stage. It is not used to supply all the crop's nutrient needs, es- pecially where nitrogen and potash re- quirements are high. Putting to test Indiana research at eleven corn sites across three years has shown how starter responses can vary in different tillage environments. In the study, responses to starters increased yields at only one site under conventional-till but at eight sites under no-till. Average yield increase across all eleven sites was 0.9 bu/A for conventional-till but 7.8 for no-till. All the sites in these studies were high fer- tility locations where starter fertilizer would not have been recommended for conventional-till. Another long-term study in southern Minnesota showed similar tillage system effects on a starter (7-21-7) response in a corn/soybean rotation. P and K soil test levels were very high. Average yield increase in corn across four years for four conservation-till systems was 9.1 bu/A compared to 5.5 bu/A for the fall plow system (Figure 1). Average yield increase in soybeans across all five till- age systems, however, was only 0.5 bu/ by Dr. Paul E. Fixen Star Star Star Star Starters R ters R ters R ters R ters Respond More F espond More F espond More F espond More F espond More Favorably in avorably in avorably in avorably in avorably in R RRRReduced- educed- educed- educed- educed-Til lage Environments Til lage Environments Tillage Environments Tillage Environments Tillage Environments Studies are showing crop responses in reduced-tillage systems outperform those in conventional-tillage. A, reflecting the tendency for soybeans to be less responsive to starter fertiliza- tion than corn. Most studies in the Mid- west, in fact, have shown soybeans tend to be less responsive to starters than corn. The early-season inflow require- ments for soybeans are considerably lower than for corn, and the physiologicaltraits of soybean roots make them less able to use nutrients in a concentrated band. Soybeans tradition- ally are planted later than corn when soil temperatures are more favorable for nu- trient uptake. However, the increase in no-till drilled soybeans has created in- terest in the possibility of using starters to maintain soil phosphate levels and provide a boost to bean yields. Re- searchers postulate that only applying phosphate in the corn years and lack of mixing may deplete soil P levels in no- till corn/soybean rotations. Research is now being conducted to explore the ef- fects of starters in no-till soybeans. Watch for future editions of the Fluid Journal for updates. A three-year Wisconsin study has shown no-till may mitigate yield loss when planting dates are delayed. Corn response to starter P and K was measured in moldboard plow and no-till systems at four different planting dates varying from April to May 24. Averaged across three years, the largest starter response in the moldboard system was 16 bu/ A, occurring at the earliest planting date. In the no-till system, response averaged -2 bu/A for the earliest date and increased for each S
Fluid Journal 1996-1998