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conditions, the growing period is defined as the period from the time when moisture
and temperature conditions are suitable for crop growth until the crops mature [3, 4, 5].
The thermal zone is one of the important parameters in agro-ecological zoning. It in-
dicates the total heat available during the growing period which can usually be repre-
sented by the heat available for the crop during each day of the growing period.
The soil property information is the basis of soil mapping. Soil types are classified as
different soil genus or soil species. Soil properties are influenced by the soil quality,
land management and even the habits of the planted crops. The land resource stock is
characterized by the combined status of land use types, and constitutes the basis of
agro-ecological zoning. The climate parameters under different scenarios are useful to
simulate and predict the spatial-temporal changes in land productivity under different
scenarios, which can be extended with climate parameters. An effective way to increase
productivity is to raise the input levels, which can include the financial investment by
governments, collectives or individual farmers in fixed and current assets. The ESLP
can estimate and simulate changes in land productivity for different input levels [6].
3 Function Modules
The ESLP estimates land productivity through an iterative method. The calculation
procedure includes five steps as following.
The potential photosynthetic productivity is the potential land productivity as de-
termined solely by the photosynthetically active radiation, based on the assumption that
the temperature, water, soil, breeds and other agricultural inputs are all in optimal
condition. It is calculated as:
YCf Q K
=
(
)
=
Ω−
εφ
(1
α
)(1
−
β
)(1
−
ργ
)(1
−
)(1
−
ω
)
1
∑
(1)
Where
Y
1
is the potential photosynthetic productivity, with the unit kg/ha;
C
is the unit
conversion factor;
K
is the area coefficient;
∑Q
j
is the total solar radiation during the
growing period (MJ/m
2
);
Ω
is the crop solar radiation utilization efficiency; ε is the
percentage of effective radiation in the total radiation;
Φ
is the photon conversion
efficiency;
α
is the reflectivity of the plant groups;
β
is the transmittance of the luxuriant
plant groups;
ρ
is the proportion of radiation intercepted by non-photosynthetic organs
of plants;
γ
is the proportion of the light that exceeds the light saturation point;
ω
is the
proportion of respiration in the photosynthate;
d
is the crop leaf abscission rate;
s
is the
economic crop coefficient;
f(L)
is the corrected value of the crop leaf area dynamics;
η
is the moisture content of the ripened grain;
δ
is the percentage of ash; and
q
is the heat
content of the dry matter (MJ/kg).
The potential thermal productivity, the upper limit of irrigated agricultural produc-
tion, refers to the land productivity determined by the natural thermal condition when
water, soil, breeds and other agricultural inputs are all in optimal conditions. It is cal-
culated from the following formula:
−
1
−
1
−
1
⋅−
(1
dsf L
)
(
) (1
−
η
)
(1
−
δ
)
q
Q
.
j
Y
=
f
(
T
)
⋅
Y
. (2)
2
1
where
Y
2
stands for the potential thermal productivity, in units of kg/ha;
f(T)
is the
temperature revision function for crop photosynthesis.
f(T)
is identified from three
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