Aerial Nitrogen Fluxes and Soil Nitrate in response to Fall-Applied Manure and Fertilizer Applications in Eastern South Dakota

Table 1

Physical characteristics and application rates of manure and urea fertilizers for experiment site.

Variable	Year	Treatment^z
		Manure with bedding	Manure only	Urea
Crop nitrogen requirement^y (kg·ha^−1)	1 & 2		242
Soil nitrate nitrogen (0–60 cm; pre-N application; kg·ha^−1)	1		113
	2	57.3 ± 7.5	44.5 ± 5.9	63.7 ± 8.4
Plant available nitrogen recommendation^x (kg·ha^−1)	1		130
	2		183
Manure moisture content (g·kg^−1)	1	742	723	—
	2	691	530	—
Manure/urea total nitrogen (g·kg^−1)	1	8.5	8.2	460
	2	8.5	11.5	460
Manure/urea^w ammonium nitrogen (g·kg^−1)	1	1.85	1.77	460
	2	1.62	1.16	460
Plant available nitrogen in manure^v/urea (g·kg^−1)	1	4.0	3.8	460
	2	4.9	6.2	460
Manure/urea application rate (Mg·ha^−1)	1	32.5	33.8	0.28
	2	37.7	29.5	0.40

^ySouth Dakota Fertilizer Recommendations Guide EC-750 [45] recommends 1.2 times corn-grain yield goal (11.3 Mg·ha⁻¹). ^xPlant-available nitrogen recommendation = crop nitrogen requirement – soil nitrate nitrogen [45]. ^wAssumes all urea-based nitrogen will hydrolyze to ammonium nitrogen in soil. ^vPlant-available nitrogen in manure = (application loss factor)  (manure ammonium nitrogen) + (mineralization factor)  (manure total nitrogen – manure ammonium nitrogen); application loss factor = 0.9 for incorporation within 24 h; mineralization factor = 0.35 for first year of manure (Y1) and 0.5 for second year of manure (Y2).