Influence of No-Tillage on Soil Organic Carbon, Total Soil Nitrogen, and Winter Wheat (Triticum aestivum L.) Grain Yield

Table 1

Treatment arrangement with preplant N, P, and K rates at E222 (Stillwater) and E502 (Lahoma), Oklahoma, USA.

Treatment number	N rate (kg·N·ha^−1)	P rate (kg·P·ha^−1)	K rate (kg·K·ha^−1)
E222
1	0	29	37
2	45	29	37
3	90	29	37
4	135^†	29	37
E502
2	0	20	56
3	22.5	20	56
4	45	20	56
5	67	20	56
6	90	20	56
7	112	20	56

N = nitrogen applied as urea (46-0-0); P = phosphorus applied as triple superphosphate (0-22-0); K = potassium applied as potassium chloride (0-0-52). ^†Split applied with 67 kg·N·ha⁻¹ preplant and 67 kg·N·ha⁻¹ midseason.