Compost and Biochar to Promote Soil Biological Activities under Sweet Potatoes Cultivation in a Subtropical Semiarid Region
Table 3
Soil concentrations of available N, P, and K during the growing season of sweet potatoes at preplanting and 39, 48, and 92 days after planting.
Treatments
Bare fallow (preplanting)
39
48
92
Days after planting
NH4+-N (µg N g−1 soil)
Control
2.34 ± 1.45
3.18 ± 2.7 aA
1.32 ± 0.37 bA
4.17 ± 3.68 aA
NPK
3.11 ± 2.81 aB
4.48 ± 1.74 aA
4.66 ± 0.8 aB
RC
0.99 ± 0.38 aA
0.95 ± 0.91 bA
2.11 ± 0.76 aA
AC
1.33 ± 0.13 aA
0.56 ± 0.27 bA
1.63 ± 0.59 aA
Biochar
1.37 ± 1.06 aA
1.11 ± 0.31 bA
1.84 ± 0.97 aA
NO3—N (µg N g−1 soil)
Control
25.97 ± 0.4
1.59 ± 0.32 aB
0.16 ± 0.19 aB
4.21 ± 2.27 bA
NPK
2.21 ± 0.81 aAB
1.92 ± 0.05 aB
11.01 ± 0.34 aA
RC
2.05 ± 1.73 aAB
0.26 ± 0.76 aB
4.31 ± 0.39 bA
AC
3.55 ± 3.39 aB
0.83 ± 1.22 aB
11.46 ± 2.12 aA
Biochar
2.29 ± 1.46 aA
1.64 ± 1.21 aA
4.16 ± 0.76 bA
P (µg P g−1 soil)
Control
0.15 ± 0.02
8.22 ± 4.86 aA
5.04 ± 0.9 aA
2.81 ± 1.44 aA
NPK
4.71 ± 0.55 aA
8.79 ± 6.48 aA
5.15 ± 1.82 aA
RC
6.43 ± 3.31 aA
3.86 ± 0.82 aA
4.45 ± 3.31 aA
AC
5.7 ± 3.35 aA
3.53 ± 1.94 aA
5.5 ± 3.34 aA
Biochar
6.67 ± 5.16 aA
4.71 ± 3.71 aA
3.38 ± 2.2 aA
K (µg K g−1 soil)
Control
36.53 ± 2.81
60.89 ± 17.17 aA
61.1 ± 14.9 abA
53.39 ± 9.43 aA
NPK
78.04 ± 11 aA
61.5 ± 21.2 abB
59.56 ± 29.37 aB
RC
65.78 ± 9.57 aA
51.9 ± 3.36 abA
49.86 ± 9.27 aA
AC
71.2 ± 13.5 aA
47.1 ± 7.64 bA
55.4 ± 4.72 aA
Biochar
69.65 ± 25.5 aA
85.9 ± 11.3 aA
67.01 ± 20.1 aA
Values are means ± standard errors (n = 3). Values within a column and nutrient followed by the same lowercase letter or within a row followed by the same uppercase letter are not significantly different ( > 0.05). Values followed by asterisk () are significantly different than preplanting values ( < 0.05). Control: no amendment; NPK: synthetic fertilizer; RC: regular compost; AC: accelerated compost; biochar: biochar produced from walnut shell feedstock.
