Iowa State University recommends that fall manure and anhydrous ammonia application not occur until the soil temperature at 4” is fifty and falling. What's changing this year is when that date is likely to arrive.

Input costs like fertilizer and limestone continue to be worrisome for farmers. Maximizing the plant availability of soil nutrients is crucial to optimizing crop production and nutrient supply to crops. One way in which to do this is by managing soil pH – actually it is one of the more important management practices. Soil pH is often overlooked when considering nutrient inputs.

Determining how much nitrogen fertilizer (N) to apply is a constant challenge facing farmers. The amount of N needed to maintain yield and healthy soils is highly dependent on weather and agronomic management, and therefore differs across years and fields (Table 1). 

To help producers, crop advisers and agricultural lenders make informed nutrient management decisions amid high fertilizer costs, Iowa State University Extension and Outreach is offering three Fertilizer and Finance workshops across Iowa this August. 

A modern 110-day corn hybrid in central Iowa produces about 19 leaves but can only maintain 12-14 leaves on the plant. The first leaves begin senescing around the V5 stage, and by silking (R1) approximately 6-8 bottom leaves have already senesced (Figure 1). From R1 to R5, leaf senescence progresses slowly, with about 2-3 additional leaves senescing. Most leaves are rapidly senescing near physiological maturity (R6) or black layer.