Agriculture Reference
In-Depth Information
Three soil samples for assessing the SOC concentration from one treatment were
obtained for 0-20 cm depth from all sites before the harvest of wheat every year.
The SOC concentration was determined by the wet combustion method (Tiessen and
Moir 1993), the bulk density by the core method (Soil Survey Staff 1999), and the
texture by the hydrometer method. Soil texture ranged from silty clay loam, loam,
silt loam, to loam (Soil Survey Staff 1999). Crop rotation involved winter wheat
and summer maize in XinjiA, XinjiB, ZhengzhouA, ZhengzhouB, HengshuiA,
HengshuiB, and Xuzhou, compared with winter wheat from 1985 to 1986, winter
wheat-summer maize and spring maize after 1987 in Changping and Beijing.
7.2.2 e
xperimentAl
d
eSign
And
m
AnAgement
The eight long-term experiments had different fertilizer managements, and the rates
of application of chemical fertilizer (N, P, K) and organic manure in these treatments
(Table 7.2) were designed according to the local household (small landholder) fertil-
izer managements and the soil nutrients varying across different soil types in the
HHH. Experimental plots varied from 1 to 3 for every treatment across the long-term
experiments; however, the plot area varied from 40 to 100 m
2
(Guo et al. 1998; Zhang
et al. 2002; Zhang et al. 2005; Xia et al. 2008; Lin et al. 2009).
All farm operations were similar except for fertilizer management for different
treatments described above. Winter wheat was irrigated two to three times, and
maize was irrigated one to two times depending on the precipitation distribution dur-
ing the growing season. The volume of water used for each irrigation was 900 (9 cm)
to 12,00 (12 cm) m
3
ha
−1
. Herbicides and pesticides were applied to control weeds
and reduce insect pressure, respectively. Organic and chemical fertilizers, including
P and K, were applied as basal dose; one-third to two-third of N was applied as basal
TABLE 7.2
Application of Chemical Fertilizer and Organic Manures under Different
Fertilizer Management Treatments
Fertilizer Managements
C (kg ha
−1
)
N (kg ha
−1
)
P
2
O
5
(kg ha
−1
)
K
2
O (kg ha
−1
)
CK
0
0
0
0
UF
0
135-360
0
0
0
0
60-150
0
0
0
0
60-150
CF
0
135-360
60-150
60-150
O
500-4050
12-120
12-170
30-200
UFO
500-4050
147-480
500-4050
72-320
500-4050
90-350
CFO
500-4050
147-480
72-320
90-350
Note:
The application amount of fertilization under different treatments was calculated and synthesized
on the basis of the experimental design at the eight experimental sites.
