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Programming of irrigations

The needs of irrigation of an olive grove can be calculated from the water balance of the ground.

The ground water content at the end of a period (Sf) is equal to the content at the beginning of the period (If) plus the Effective Precipitation (Pe) except the Evapotranspiration of the culture (ETc) plus the net irrigation (Rn).

Sf = Si + Pe - ETc + Rn

Where:
Pe :it is considered for equal Andalusia to 70% of average rain.

The water content of the soil has an upper limit that can not exceed: Capacity Field (CC) and a lower limit beyond which there can not perspire cultivation: Point of marchitez permanente (PMP), which can be calculated in laboratory.

By monitoring the weather this year can be calculated irrigation net so you never get off the water content of the soil below 70% Water utility (AU), being the difference between the AU capacity Campo ( CA) and the Point de marchitez Perm (PMP).

In fact, although it seems complicated, simply one is to take the balance of the water content in the ground and not to allow that content descends from 70% of the Useful water. The problem of this method is that the factors that not always enter game in the previous balance are easy to calculate.

ur experience recommends a method to us of application of the irrigation, very simple, that it works with excellent results in the olive grove in our climatologic conditions (Valley of the Guadalquivir).

It is applying the available water distributed in the summer, namely budding or spring rains last until the first rains of autumn. So, if we have 1,800 m3/ha for a plantation of 100 olive trees/Ha get excellent results by applying 100 liters per day/olive during 180 days of summer (from April 1 to September 30. Occur naturally as the rains this year and based on weather forecasts is due to advance and expand and reduce or delay the implementation of water, always seeking to link the past with the first spring rains autumnal rains. It can only be a final recommendation to reduce evaporation losses directly from the bulb moisture drip and implement the dose is calculated every few days (5-7).

This method of programming of irrigations has important properties:

  1. It is ideally suited to the development of phenological olive grove.
  2. The installation of irrigation necessary to implement this water is the most economical way.
  3. The programming shift irrigation is simple and convenient.
  4. The consumption of electrical energy required for the installation can be easily minimized by using energy at off-peak hours.
  5. It applies an excess of water on the olive tree Etc. at the beginning of summer in the first stages of development and flowering vegetation and at the end of summer in the second vegetative development. Nobody doubts that rainy springs and autumns have always been good omens for the olive harvest.

If it were not had a continuous volume serve the previous considerations, that is to say, to apply 50% of the water of irrigation at the beginning of the summer period, trying to reach the Capacity of Field at the advanced moment more possible of the spring to guarantee a summer without hydric deficit obstacle and the other 50% at the end of the summer, before a hydric deficit takes place, to connect with the first autumnal rains.

This method of programming practically does not fail never with the exception of grounds with great limitations or in years of prolonged drought.

In case it is considered essential to adapt the programming of irrigations to the evapotranspiration of the olive grove is possible to be corrected, for the Valley of the Guadalquivir, the water applied based on the coefficients of the following table:

April May June Julio August Sept.
0,700,901,101,301,100,90

That is, for example previously applicable 70, 90, 110, 130, 110 and 90 litres per day / olive in April, May, June, July, August and September respectively, instead of 100 litres per day / for olive throughout the period.