Agronomy Guide 2009–2010

Part 1, Section 4: Corn

Section 4 Table of Contents

Corn

NUTRITIONAL REQUIREMENTS

Basic fertility management

Lime, phosphate (P₂O₅), potash (K₂O), and magnesium (Mg) requirements are best determined by soil testing. Soil test recommendations take into account the yield goal or the crop yield potential for the soil type, the fertility level of the specific soil, and projected crop nutrient removal. Nitrogen (N) fertilizer recommendations are based on the yield potential of the crop and the contribution of previous legume crops. On manured fields, sidedress nitrogen requirements also can be estimated using the presidedress nitrogen soil test. For a more detailed discussion of basic soil fertility management, see Section 1.2, “Soil Fertility Management.”

Adjusting recommendations

To determine the amount of commercial fertilizer required to produce a corn crop:

• Determine total nutrient requirements from soil test recommendations or, in lieu of a soil test, from Table 1.2-5.
• Adjust the recommendations for manure applications using Tables 1.2-13, 1.2-14, and 1.2-15. (See Table 1.4-2 for an example.)
• If you did not check the appropriate previous legume crop on your soil test questionnaire, adjust the nitrogen recommendations using Table 1.2-8. (For an example, see Table 1.4-3.)
• Determine the amount of N-P₂O₅-K₂O to be applied as row (starter) fertilizer and subtract this amount from the adjusted recommendation to determine broadcast or plowdown requirement. (For examples, see Table 1.4-2 and Table 1.4-3.)

Table 1.4-2. Example of adjusting plant nutrient recommendations for manure applications (corn following manure application, manure incorporated immediately).

	Plant nutrients (lb/A)
	N	P2O5	K2O
Recommendations for 125 bu/A	130	100	80
Row fertilizer, 200 lbs 10-30-10	20	60	20
Cattle manure, 12 tons	60	36	60
Total credits	80	96	80
Additional needed	50	4	0

Table 1.4-3. Example of adjusting plant nutrient recommendations for previous crop (125 bu/A corn following a legume).

	Plant nutrients (lb/A)
	N	P2O5	K2O
Recommendations for 125 bu/A	130	100	80
Row fertilizer, 200 lbs 10-30-10	20	60	20
Previous crop, alfalfa 50% to 75%	110	0	0
Total credits	130	60	20
Additional needed	0	40	60

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