New big projects of high density groves in Chile

Transcription

1 New big projects of high density groves in Chile Xavier Rius Agromillora Australia Agricultural engineer 1.- Introduction In July 2007 I had the opportunity to travel with the manager of Agromillora Sur, from the seventh region or Maule to the fourth region or La Serena covering an area of 1200 km from south to north, to see the big projects of high density olive groves that the nursery is carrying out. Also the aim of the trip was to share experiences with the agronomists and managers of these projects in regards the management of the groves. Agromillora Sur nursery with 100 employees and sales of 6 million trees a year The location of the orchards in the north (La Serena) or in the south (Curico) determines the characteristics and management of the orchards according to their climate. In the north dry and very hot with 200 mm of rainfall and in the south cool and wet with 700 to 1000 mm of rainfall. 2.- Varieties The varieties used in all projects are Arbequina I-18 in 60 80%, Arbosana I-43 in % and Koroneiki 5 10 %. Planting spaces are for Arbequina I-18 and Koroneiki; 4*1,5 m and Arbosana 4 *1,35 meters. In areas with frost risk is all planted to Arbequina. Productions are sustainable year after year between tn /ha. Black scale and repilo are the pest and diseases more frequent. 1

2 Foto: 1000 Ha grove of Arbequina I Aspects of soil management and irrigation 3.1.-Soil management It s remarkable the good planning in the development of the projects starting with a soil survey and the irrigation design in blocks to be able to irrigate soils with same characteristics. Foto: 1000 Ha new Project In the groves in the south it is common to mound the soil up to 50 cm height to avoid waterlogging in certain areas with poor drainage and in other areas to increase root depth due to a compact layer near the surface. Usually this compact layer is cemented sands impeding root growth and water penetration. This layer varies in depth and if it s present in the first 80 cm and not too thick can be broken with ripping. In the groves in the south the excess of water was one of the major problems due to heavy rains in winter and spring 2

3 Photo; 200 ha grove. Mounding to 50 cm to avoid waterlogging of rootzone In the areas with poor drainage due to topography (low areas) it has been necessary to install drains to control the level of the water table, also as a temporary measure it has been to open a channel to evacuate the water. Photo: Channel in the perimeter of the property to eliminate excess water Due to heavy winter rains in 2007 in some groves has been necessary to break the mounding in some areas to allow quick evacuation of the water. In some groves are showing symptoms of high soil moisture levels with poor aeration for long period of time limiting root growth (superficial and small roots). Soil waterlogging also can create; Limiting the use of machinery to avoid soil compaction. Soil ph variations that affect nutrients availability. Induction to iron chlorosis. The use of cover crops with deep roots such as Lucerne or cereals is helping to fracture the compact layers and absorb some excess water. 3

4 During soil preparation is common to use calcium carbonate up to 8 tn/ha to increase ph values to 6, In the other hand, in the north of the country the soils presented high ph with values around 8,5 with high calcium carbonate content and petrocalcic horizon in some areas. Also it is common to use mounding the soil for salinity management and increase root depth in areas with carbonates close to surface Fertilizers In the south soils are very fertile and to avoid any excess vigour in the trees the use of fertilizers is limited. The fertilizers most frequently use are ammonium nitrate and calcium nitrate. It is a common practice to program fertilizer inputs according to leaf analyses and production levels. Boron and zinc applications by foliar are frequently used. Almost all the irrigation systems are drip. It is common to apply phosphoric acid through the irrigation system in the groves in the north with soils with high ph to make the micronutrients more available (Zn, Fe, Mn, Cu). Annually ph and EC testing is carried out in the rootzone under drip influence and in the middle of the row to compare any possible changes Irrigation scheduling In most of the groves irrigation scheduling is based on weather data, Pan evaporimeters and opening pits to check manually soil moisture levels. In all the groves irrigation system was drip with 3,5 l/h and 75 cm spacing in the south and 2,3 l/h and 50 cm spacing in the north. In the south in areas where ripening could be delayed by rain it is common to reduce soil moisture levels with the aim to advance maturity. Soil moisture and fertilizers are kept high during the first 2 years of the grove development, when the plants have formed the canopy its necessary to adjust water and nutrients requirements to keep it in balance and avoid to much vegetative growth. 4

5 Photo: 200 Ha grove of 1 year In the groves in the north with salinity problems a detailed monitoring program has been put in place with suction lisimeters at different depths (20 y 60 cm), ph and EC measurements, nitrates and ammonium. In some orchards electrical conductivity of irrigation water varies from 2,8 a 4 ds/cm. Photo: 500 Ha new groves with soil mounding for salinity management Calcium is added to the soil to manage the sodium in the irrigation water and avoid soil sodification. Potassium is regularly applied due to levels in the soil are marginal. 5