I. Calculation procedure for irrigation rates estimation and ecologically safe irrigation scheduling, which is based on natural heat and moisture potential content account and on their deviation over the territory with a time pass.
The main advantage of procedure developed in VNII “Raduga” is its software equipment.

II. Software

III. RF territory is divided into some areas (regions) according to the moisture content K _y value (Central Non-Black Earth Region, Central Black Earth Region, the Ural Region, Altai Territory, Western Siberia, etc).

IV. Irrigation scheduling and irrigation rates estimation over RF regions for different farming crops under different natural heat and moisture content conditions.

Data base (resources):

• ten days period meteorological data of air temperature and moisture content, wind velocity and precipitation rate (no less than 40-60 years of observations) for main RF regions.
• biological and climatic as well as micro climatic coefficients for natural zones and crops.

Service:

We can provide irrigation scheduling after contract signing for every RF region as well as ecologically safe irrigation scheduling and irrigation rates forecasting and dividing territory into regions.

ProcedureInitial data

• ten days period meteorological data of air temperature and moisture content, wind velocity and precipitation rate (no less than for 40-60 years of observations);
• mechanical composition, water and physical conditions as well as chemical soil characteristics of the root and aeration zone;
• farming crops, vegetation period, growth rate, root zone depth;
• irrigated area size, biological and climatic as well as micro climatic coefficients over natural zone and crops.

Calculation order

• calculated crop water consumption period estimation;
• potential evaporation rate (evapotranspiration rate) for ten days is calculated for the estimated period;
• by biological and climatic and micro climatic coefficients for ten days period optimal crop water consumption (evapotranspiration) is calculated;
• if ground water horizon is close to the surface its capillary use is estimated (for ten days period);
• soil active moisture content is also calculated for every ten days of vegetative period according to the root zone depth;
• water balance equation solution gives water use deficit values for ten days period, their sum for the vegetative period is net irrigation depth.

Calculation model

Evaporation rate E, mm is estimated from the equation:

The equation components are calculated from the following functions:

t – air temperature, °С;

- saturated air elasticity at this temperature, мb;

d – air moisture deficit, мb;

А – relative air moisture content, %;

f(u) – wind function;

u₂ - wind velocity at 2,0 meters above the earth surface m/s;

u_f – weather-vane wind velocity, m/s;

γ- coefficient for wind velocity at 2,0 meters above the earth surface reduction.

Values of and γ are taken from the tables in meteorological reference books.

Natural moisture coefficient К_у :

where: W_a – active moisture content in the root zone soil layer at the beginning of the farming crop vegetative period, mm;

Р – summarized precipitation depth for the calculated time period, mm;

Е – evaporation rate for the same period, mm.

Optimal water consumption E ν :

where: Е – evaporation rate, mm;

К_б – biological and climatic coefficient;

К_о – micro climatic coefficient.

Biological and climatic coefficients К_б reflect the plants role in moisture consumption on the farm field. Their values are estimated experimentally during irrigation scheduling investigations. These values are specific for different crops because of their growth biological biologic rhythm difference. in accordance with air temperature summarized values from the vegetation period beginning the biologic-climatic coefficients are entered computer program.

For certain years different from the mean many years value, the current К_бi values are estimated from a real year data:

where:

К_бо – mean coefficient value for many years calculated interval;

Е_о- mean for many years evaporation rate value for the same time period, mm;

Е_i- real year evaporation rate value, mm;

Micro climate coefficient К_о estimates probable meteorological factors change on the farming field after irrigation event.

К₀ values for irrigated area with the size from 100 up to 1000 ha:

Ку	0,2	0,3	0,4	0,5	0,6	0,7	0,8	0,9	1,0	1,1	1,2
К0	0,85	0,88	0,91	0,93	0,95	0,96	0,97	0,98	0,99	0,99	1,0

If there is a weather station on the irrigated field, К₀=1,0.

Net Irrigation Depth М_нт, mm:

where: М_нт - net irrigation depth, mm;

∆Е _v – crop water consumption deficit for the calculated period (ten days, a month), mm;

Е_v – optimal crop water consumption for the calculated interval, mm;

W_а – active moisture content in working soil layer at the calculated period

beginning, mm;

Р – precipitation depth for the calculated period, mm;

G – capillary ground water consumption, mm;

Y - moisture outflow from the irrigated field borders, including surface and depth outflow, mm;

Actively (freely) used by plants moisture content is:

where: W_нв – moisture content in 1 meter soil layer, equal to the mean water holding capacity of the field (water holding ability) of the field, mm;

µ - coefficient evaluating a real soil moisture saturation at the beginning of the calculated period as a part of W_нв , changing from 0,7 up to 1 over the natural zone and for different crops;

β₀ – soil moisture content equal to pre irrigation limit (allowable drying level),

as part of W_нв , is estimated in experimental way.

Capillary use of the ground water is estimated from a function:

where: q_г – ground water use coefficient, as a part of Е_v, estimated in an experimental way for each region.

Forecasted irrigation parameters evaluation is made by possibility (availability) curve, which allows stress certain parameters for the years of different moisture availability:

5% и 25% -wet years;

50% - mean year;

75%, 85% и 95% - dry years.

Computer software:

Computer program has official registration Certificate № 2003611339 under the title «RRORK.BAS».

Since 2003 irrigation scheduling calculations are made by newly developed and modernized program with official registration Certificate № 2004610996. This program is used under a title «ROCK.xls». Modernized in 2005 Computer Program «ROCK.xls» assures investigated parameters calculation for any time period longitude, making their statistic analysis and their change dynamics evaluation.

To perform the calculations for the steppe regions of the European RF part we developed computer program «ROSK.U».