(
)
(
)
(
)
−
+
−
+
−
−
−
=
t
t
t
t
t
p
p
p
p
B
t
p
k
1
2
/
2
/
2
/
2
/
2
, (5)
where
- specific weight of water - 9,81 N/m
3
;
(
р+р/2
—
р--р/2
)/р - derivative
(in finite difference form) of volume moisture by р;
(
t+t/2
—
t-t/2
)/t - derivative (in
finite difference form) of volume moisture by t;
(
t
—
) - the amount of moisture
remaining in the soil from the moment of determination to the achievement of the
equilibrium (the proportion of the fate of one); coefficient
, m
2
(0,1 to 2,2).
The calculations of irrigation norms of the main crops are presented, the algorithm
of optimal decision making in irrigation planning is considered, the economic and
ecological efficiency of the proposed approach is estimated.
For agricultural crops (winter wheat, second hand alfalfa, sugar beets, corn for
grain and maize for silage) the optimal irrigation rates were calculated in years of
different water supply and at different water charges. System estimates for the
additional net profit from irrigation, depending on the irrigation rate, the amount of the
payment for water, in the years of different water availability and their corresponding
irrigation regimes are shown in Fig. 4
The economic efficiency of the method ΔDCP (Table 1) can be determined on the
basis of comparison of the additional net profit from irrigation while conducting
agricultural production on the basis of traditional - biologically optimal water use and
proposed cost-effective water use in specific conditions of payment for water, in certain
years water availability, in relation to economic conditions of the consumer (sales
prices, costs, etc.). In addition, in the option of economically optimal water use water
resources savings ΔM (Table 1).
a
Prof
it
,
uan/
ha
Irrigation rate, m3/ha
Additional net profit from irrigation
0 uan
0,05
uan
В
BО
- 1318 -