Table 5 Relationship of cotton root length in the 20~60 cm soil layer, dry matter accumulation of above-ground cotton at the boll opening stage and cotton lint yield to soil total N, available P, available K content in different soil layers in 2014 and 2015
From: Soil replacement combined with subsoiling improves cotton yields
Dependent Variable (Units) | Year | Soil layer (cm) | Regression equation and coefficient of determination (R2) | ||
|---|---|---|---|---|---|
Soil total N content (g kg−1) | Soi l available P content (mg kg− 1) | Soil available K content (mg kg− 1) | |||
Root length in 20~60 cm soil layer (cm) | 2014 | 0~20 | −2 149.5x + 2 457.8 (0.7266) | − 104.0x + 3 450.4 (0.6411) | −8.2x + 2 515.9 (0.8439) |
20~40 | 4 203.5x-676.1 (0.9269*) | 60.1x + 545.7 (0.9373*) | 16.0x-246.6 (0.7079) | ||
40~60 | 8 076.1x-2 101.6 (0.111) | 71.0x + 859.1 (0.9911*) | 18.7x-322.5 (0.9968*) | ||
2015 | 0~20 | −3 772.1x + 2 825.1 (0.7949) | − 157.4x + 3 511.1 (0.5383) | −22.2x + 3 152.7 (0.7895) | |
20~40 | 3 495.4x-830.0 (0.8777) | 61.2x + 68.9 (0.7760) | 22.2x-996.6 (0.6283) | ||
40~60 | 13 797.0x-4 947.7 (0.7162) | 105.8x + 280.1 (0.9838*) | 33.7x-1 250.8 (0.9825*) | ||
Dry matter accumulation of above ground cotton at boll opening stage (g plant−1) | 2014 | 0~20 | − 273.9x + 359.5 (0.8031) | − 13.7x + 494.5 (0.7520) | − 1.04x + 365.9 (0.9204*) |
20~40 | 506.0x-26.3 (0.9143*) | 7.5x + 118.2 (0.9824*) | 2.0x + 16.9 (0.7664) | ||
40~60 | 1 097.7x-249.9 (0.1397) | 8.5x + 159.1 (0.9560*) | 2.3x + 16.7 (0.9796*) | ||
2015 | 0~20 | −400.7x + 408.7 (0.9351*) | −17.6x + 496.7 (0.6998) | −2.28x + 435.4 (0.8715) | |
20~40 | 303.7x + 50.6 (0.6907) | 6.8x + 112.9 (0.9916*) | 2.4x-3.5 (0.7900) | ||
40~60 | 999.1x-225.0 (0.3915) | 9.3x + 146.5 (0.7948) | 3.1x + 4.3 (0.8635) | ||
cotton lint yield (kg ha−1) | 2014 | 0~20 | − 684.1x + 2 148.4 (0.7486) | −33.8x + 2 478.81 (0.6881) | −2.6x + 2 168.7 (0.8775) |
20~40 | 1 325.8x + 1 156.5 (0.9380*) | 19.1x + 1 540.1 (0.9639*) | 5.2x + 1 278.7 (0.7574) | ||
40~60 | 2 860.4x + 577.1 (0.1417) | 22.1x + 1 642.1 (0.9808*) | 5.8x + 1 272.9 (0.9888*) | ||
2015 | 0~20 | −968.1x + 2 170.5 (0.6267) | −44.3x + 2 415.7 (0.5106) | −5.3x + 2 211.4 (0.5390) | |
20~40 | 563.2x + 1 381.4 (0.2728) | 17.2x + 1 447.1 (0.7329) | 6.1x + 1 161.3 (0.5609) | ||
40~60 | 1 211.8x + 1 134.1 (0.0661) | 17.5x + 1 558.4 (0.3221) | 6.2x + 1 268.5 (0.3979) | ||