September 16, 2019: Finishing 2019 with 2020 in Mind

September 16, 2019

Fertilizer plans for 2020 require a good thought process.  We must take into consideration a number of factors already evident in the 2019 crop as we plan our fall and spring fertilizer programs for the 2020 crop year.
First, corn and soybean planting was seriously delayed for several weeks this spring on millions of acres.  Then, many planted acres were mudded in just to get them seeded. Standing water from excessive rain and flooding drowned out a tremendous number of acres and, no doubt, a good deal of nitrogen was lost due to leaching and denitrification particularly in the low lying areas of many fields.  Soil crusting caused various seedling emergence problems and uneven plant uniformity.  Working wet soils probably created soil compaction.  Some acres were not able to receive sidedress nitrogen to compensate for early nitrogen losses.  Post emergent weed control was sometimes not as timely as it should have been.
There will be a tremendous amount of yield variability across many fields.  The uplands and side slopes are looking pretty good, but the low ground is suffering.  We normally adjust fertilizer application based on average yields across a field, but this year it might be wise to take a close look at in field yield variability.
For instance, low yielding areas will have lower removal rates of phosphorus and potassium.  The use of yield monitors, yield and soil nutrient maps, recent site specific soil samples and variable rate fertilizer application may really pay off in 2020.  Applying fertilizer where it is most needed and most beneficial has always been a goal of Smith Fertilizer and Grains’ precision agriculture, but the in field variability we’ve seen this year may make it easier to identify areas that should really be managed differently.
The question of fertilizer carryover often comes up in years with reduced yields.  On sandy soils potassium can be lost due to leaching.  A soil test would be wise if you suspect potassium loss.  If you have yield maps or can visually identify problem areas, soil sampling in the low yielding areas can help the decision making process for next year.  Unless you have a known problem with phosphorus fixation, it is probably safe to assume that phosphorus applied for the 2019 crop, not utilized,  will become a part of the residual available soil P.  Again, fresh soil samples can help identify potential problem areas.
Variable rate fertilizer application across fields may be particularly beneficial this year.  With the potential for large yield differences among fields and within fields, nutrient removal will be equally variable.  In addition to differences in nutrient removal, there could be differences in nutrient carryover as well.  With a little detective work, Smith Fertilizer and Grain agronomist should be able to help you figure out where fertilizer will be most needed by the next crop.
We should also be able to determine if soil compaction is an issue.  Tools such as a soil probe can be used to find areas of compaction and determine their severity.  Smith Fertilizer and Grain agronomists normally see compaction on the ends of the fields in the turn rows but, in wet years, it can be created nearly any place.  Tillage implements as well as tire traffic can cause compaction.  Where compaction is a potential problem, deep tillage can help break it up, but the soil must be dry in the compacted zone.  Deep tilling a wet or moist soil will not break up compaction, and may even make it worse.
Making fertilizer decisions is always based on multiple factors.  Because of the unusually  late planting and wet soils this year, Smith Fertilizer and Grain agronomists and you have a few more to consider.  Regardless, good soil fertility, with fertilizer places where it is needed and when it is needed, still pays dividends.  This year was unusual, but the fundamentals of good soil fertility and crop profitability haven’t changed.
Posted: 9/16/2019 9:24:46 AM by Rob Matherly | with 0 comments