Fertilizing Olive Trees

Transcription

1 HELLENIC AGRICULTURAL ORGANIZATION DEMETER Fertilizing Olive Trees Dr Georgios Psarras Institute for Olive Tree & Subtropical Plants Lab of Plant Mineral Nutrition & Physiology Introduction Max yield Potential Law of Minimum (von Liebig) 1

2 Plant Growth 24/10/2016 Introduction DEFICIENCY ADEQUACY TOXICITY Nutrient concentration In leaves Plant Nutrient Requirements Macronutrients Nitrogen (Ν) Phosphorus (Ρ) Potassium (Κ) Calcium (Ca) Magnesium (Mg) Sulphur (S) Micronutrients Iron (Fe) Manganese (Mn) Zinc (Zn) Boron (Β) Copper (Cu) Molybdenum (Μο) Chloride (Cl) 2

3 Sustainable fertilizing schedule A sustainable fertilizing schedule has to: Retain nutrient concentration within adequacy range Avoid deficiencies Avoid toxicity Retain nutrient balance Replace nutrient removal from the orchard (removal from yield, pruning, etc.) Use of chemical fertilizers Use of organic fertilizers or other organic material Recycling of material removed from the tree (prunings, olive oil by-products, etc.) Sustainable fertilizing schedule Appropriate application scheduling: Reduce fertilizer losses Apply nutrients during the high nutrient demand season Protection of the environment Improve soil fertility Increase of organic matter Maintain ph within the appropriate limits for olive Improve soil texture 3

4 Defining nutrient requirements Defining nutrient requirements is a key issue for a sustainable fertilizing schedule There are some basic estimates of nutrient removal, mostly based on tree yield that will be presented later on However, these estimates may vary considerably and data for local conditions and/or cultivars should be available, since olive tree is cultivated under significantly variable orchard management schemes Natural vs intensive management Several of the traditional orchards are typically adopting low-input management scheme, resulting to a low-output (yield) too. The potential for converting this low-input system into a more productive but also more intensive scheme, greatly depends on the existing abilities to overcome current restrictions. 4

5 Olive tree growing systems Growing system % world-wide Density (trees/ha) Traditional in marginal areas Traditional able to be mechanized 20 Up to Up to 100 Intensive 29 Up to 400 Hedgerow Source: Tous et al., 2011 Empirical vs sustainable In several cases, the existing pool of nutrients in the soil is considerably higher than actual nutrient removal and therefore, especially in traditional olive orchards, the need for fertilizer use is limited for most of the essential mineral nutrients Since the actual nutrient requirements cannot easily be calculated, even by agronomists, for a specific orchard, it is obvious that empirical application of fertilizers by farmers may lead to serious mistakes that may increase the production cost and definitely reduce the efficient use of resources 5

6 Important knowledge and tools Knowing the nutritional status of the tree: Leaf analysis Knowing key soil properties and indicative nutrient availability: Soil analysis Olive tree fertilizing The nutrients that are most commonly used for olive tree fertilizing are N, P, K and B In several cases and depending on local soil properties, Ca and Mg might also be used, as well as the rest of mineral elements in case of proven deficiency For every 50 kg of olive fruit produced, the amount of nutrients that are removed are: 450 g N, 100 g P, 500 g K and 200 g Ca 6

7 Olive tree nutrient removal by yield and pruning According to Fernandez-Escobar et al., 2015: N kg/ha P kg/ha K kg/ha Ca kg/ha Amount Main Source Yield and Pruning Yield Pruning Introduction Annual requirements for mineral elements vary considerably among different orchards depending upon: Tree age Planting density Cultivar Pruning Rainfall and availability of irrigation water Soil characteristics: Soil texture Soil carbonate content Soil organic matter 7

8 IRRIGATED RAINFED 73% 27% Low Normal Nitrogen 42% 58% Low Normal IRRIGATED RAINFED 41% Low Potassium 35% Low 59% Normal 65% Normal Nitrogen Typically, in fertilized orchards, N is added on an annual basis Typical Mediterranean soils are low in organic matter and therefore: Plants use almost exclusively the N added through fertilizers It is important to replenish soil N resources Olive tree responds to N fertilizing in various ways 8

9 Nitrogen Increased yield Higher flowering quality Longer shoot growth Reduced biennial bearing fluctuations Nitrogen cycle in the farm N-fixing plants Mineral N Fertilizing Ν 2 Atmospheric Ν Organic Ν (Manure, Compost, etc) NH 3 Ammonia Soil Organic N N fixation Mineralization ΝΗ 4 + Αμμωνιακό Ν Uptake by Olive trees Nitrification ΝΟ 2 - ΝΟ 3 - Nitrate-N Leaching 9

10 Nitrogen N losses depend upon climatic conditions (rainfall events), soil type and orchard topography (slope) NO 3 -N leaching High rainfall Coarse soil texure, Low organic matter Atmospheric losses Hot and dry environment High soil CaCO3 content (calcareous soil) Flooded soil (anaerobic conditions) Surface runoff losses Orchards on high slopes and increased soil erosion risk High rainfall rates after application Nitrogen Long-term experiments in Crete showed that addition of 0,8 kg N/tree can increase yield by % as compared to nonfertilized control trees. N fertilizing increases: the number of perfect flowers The length of annual shoot growth The number of nods per shoot The number of inflorescence No effects on fruit drop percentage and total number of flowers per inflorescence Shoot growth starts earlier, an advantage for rainfed orchards. Flowering and fruit set are also completed earlier. 10

11 Nirogen Low N content short length of annual growth and pale leaf color (chlorosis in whole leaf surface) High N content long annual shoot growth, low yield, dark green leaf color Long annual shoot growth no flower differentiation Very short annual growth low yield potential for next year Therefore, a balanced N fertilizing is required for achieving a good yield Nitrogen deficiency Source: Production Techniques in Olive Growing. IOC,

12 Nitrogen Typical annual requirements of olive trees range from kg Ν per tree (not exceeding 150 kg/ha) depending mostly on: Tree size Planting density Water availability If reduced water availability severely inhibits plant growth and yield, then total N uptake (and fertilizing need) is also significantly lower In rainfed orchards, high N application rates may reduce uptake of other nutrients, like K Nitrogen and fruit/oil quality Experiment: cv. Picual in 2 areas with N applied either 100% from soil or (soil-foliar appl.), after 3 years: Total phenolic content was reduced as N content was increased reduced oil tolerance to oxidation and reduced bitterness. Tocopherols were increased as N content was increased. No effect on carotenoids, chlorophyll, and fatty acid composition. Source: Fernández-Escobar et al.,

13 Nitrogen and olive oil quality Higher doses of N and P: Decreased polyphenol content Decreased peroxide value Decreased MUFA C18:1 Increased PUFA C18:3 K dosage did not affect oil quality parameters Source: Dag et al., 2009 Phosphorus Under field conditions, olive tree yield is not affected by P application in most cases. However, low P content has been recorded in areas cultivated for the first time (new orchards) and in acidic soils in Crete. Use of composite fertilizers usually leads to P surplus in leaves and high levels of P in the soil. Nonetheless, P is a quite important element for olive tree, as in any other plant, and we have to be sure that trees have adequate P levels. 13

14 P and fruit yield Source: Erel et al., 2008 Phosphorus and olive oil quality Higher doses of N and P: Decreased polyphenol content Decreased peroxide value Decreased MUFA C18:1 Increased PUFA C18:3 K dosage did not affect oil quality parameters Source: Dag et al.,

15 Phosphorus Phosphorus in the soil Phosphorus is strongly bound in the soil and only a small part is available to the tree P movement in the soil is very slow (in contrast to N). The highest risk for P losses is related to soil erosion in sensitive areas Phosphorus Visual symptoms of P deficiency in the field is quite rare. Therefore, leaf analysis is usually the only way to detect P deficiency When P leaf content is marginal or low, winter application of P usually solves the problem. Typical rates for medium-sized trees are kg P 2 O 5 /tree However, the exact rate of application should be defined taking into account various soil properties 15

16 Potassium Potassium deficiency is quite common in olive orchards K deficiency is more common in rainfed orchards, where high K requirements coincide with the peak of the dry season Typical symptoms: chlorosis developing to necrosis of leaf tip and/or leaf edges. In severe cases: leaf drop and shoot necrosis. In such cases severe impact on yield. K deficiency symptoms in leaves, shoots and fruit Source: Production Techniques in Olive Growing. IOC,

17 Potassium A typical dose for trees with a mean annual yield of 50 kg of olives is 0.5 kg K 2 O/ tree This is the maintenance dose when soil and leaf content are within the adequacy range. When there is a strong biennial bearing cycle, then K is preferably applied when the high yield is expected ( on year). In cases where soil K content is significantly low, then the application rate may be double or triple than actual tree requirements, depending on soil type, in order to restore K availability in the soil. Calcium Ca deficiency is not quite common, since olive is traditionally cultivated in calcareous soils. Typical symptom is leaf tip chlorosis In table olives, Ca has been related (together with B) to fruit abnormalities (soft nose) Use of fertilizers than can lower soil ph may enhance the Ca deficiency problems Significant Ca deficiency problems have been observed in soils with high Mg content 17

18 Ca deficiency symptoms in olive leaves Calcium Low Ca levels are typically linked to soils with low CaCO 3 content and low ph. In such soils, soil liming is recommended anyway, in order to improve soil ph. This practice usually improves Ca uptake and resolves the problem. When soil ph is not a limiting factor (i.e. >6.5), then fertilizers with readily availables forms of Ca are applied (i.e. calcium nitrate) 18

19 Magnesium Typical symptoms of deficiency: chlorosis developing from leaf edges and developing inwards. Symptoms develop in older leaves. Not a common deficiency in Greece, due to existing soil types However, it is an important macronutrient, which should be monitored by leaf analysis and be included in fertilization scheduling if levels in leaf and soil are low Magnesium Source: F. Nigro,

20 Magnesium Similarly to Ca, low soil availability is linked to low soil ph. When low Mg levels are detected in a low ph soil, then liming with dolomite (containing both Ca and Mg) should be applied. When soil ph is not a limiting factor (i.e. >6.5), and leaf analysis shows low Mg levels: Soil or foliar application of MgSO 4 can resolve the problem (up to 2 kg/tree for soil application, repeated periodically) Maintenance with Mg-containing fertilizers (e.g. K-Mg sulphate) Boron The most common micro-nutrient deficiency for olive trees. Common to many different soil types, like coarsetextured soils (B lost by leaching), fine-textured soils, low or high soil ph (reduced B mobility in soils with high clay, or carbonates or Al, Fe, Mn oxides) Soil moisture greatly affects B availability High organic matter in the soil can improve B release to the nutrient solution 20

21 Boron Symptoms appear in both young and mature olive trees, but deficiency develops faster in young trees Step 1: Leaf tip chlorosis that develops to necrosis. Leaves might have flattened tips and be smaller in size Step 2: Shoot growth is limited and lateral buds develop instead of shoot-tip buds, resulting in Witch s broom symptom. Step 3: Shoot necrosis and leaf drop Boron Brown necrotic spots may develop in thicker shoots Under B deficiency, flowering is limited and fruit-set is lower than normal. Fruit drop and deformation of remaining ( monkey face symptom) are also typical Despite the great variety of symptoms in several cases it can be confused with other nutritional problems Therefore, leaf analysis is again quite useful in early detection of B deficiency, before developing severe symptoms 21

22 B deficiency in leaves and fruit of cv. Throubolia Boron Controlling B deficiency: When B deficiency is diagnosed, typical treatment is the application of g of Borax per tree (could be even higher for very large trees) during winter. Depending on soil type (especially in calcareous soils) response to soil application may be delayed or limited Alternatively: foliar application of Borax (0,6-0,8 %) before flowering Quick response 22

23 Boron Soil application should be repeated every 3 years Over-dosing in B application may lead to B toxicity Use of composite fertilizers containing small amounts of B could be effective for maintenance, but may not be adequate for correcting a severe deficiency Other micro-nutrients Deficiencies of zinc and copper are not as common. In general, micronutrient deficiencies are linked to alkaline soil ph 23

24 Zinc Despite the fact that olive is typically cultivated in calcareous soils with high ph, where Zn availability is low, in general, olive tree is not as sensitive in developing Zn deficiency as other tree crops (e.g. citrus) However, in recent years several cases of Zn deficiency have been detected Recent work has linked Zn deficiency to high P levels in soil and olive trees Copper Rarely found in low concentrations in leaves Usually, application of Cu-containing fungicides also covers (in surplus) the olive tree requirements 24

25 Iron Iron deficiency symptoms have been detected in olive trees grown in calcareous soils with high ph Flooding conditions in the soil may enhance Fe deficiency problems Cultivar seems to be the most important factor in developing Fe deficiency in calcareous soils Symptoms: leaf yellowing with veins remaining green, loss of vigor and reduced yield Fruit are smaller and pale in color (disadvantage for table olives) Iron Iron deficiency is not easily detected by leaf analysis. Therefore, it is the only nutrient deficiency that is better detected by the visual symptoms in the trees (linked to soil analysis) Difficult to correct (high cost) Therefore, avoid its development is better than trying to resolve the problem 25

26 Iron Planting non-sensitive cultivars in calcareous soils is essential Using a tolerant cultivar as rootstock could be another alternative Reference Sensitive Less sensitive Tolerant Pastor et al., 2002 Arbequina, Manzanilla de Sevilla Cornicabra, Hojiblanca, Nevadillo negro Alcantara et al Leccino, Arbequina, Lechin de Sevilla, Galega Cornezuelo de Jaen Nevadillo negro, Pajarero, Manzanilla de Sevilla Iron Source: Franco Nigro, 2015 Fe deficiency symptoms in leaves and fruit Source: Production Techniques in Olive Growing. IOC,

27 Toxicities NaCl toxicity B toxicity Mn toxicity In summary N is typically applied on an annual basis P is usually in surplus in soil and leaves when compound fertilizers have been used for several years In highly productive trees, K is also used on an annual basis, due to significant removal by the produced fruit B has to be periodically applied in most olive orchards 27

28 Defining mineral nutrient requirements For defining the nutrient requirements and develop a fertilizing schedule, the agronomist should have in hand the following information: Informative material on key orchard characteristics: Age, density, tree size, water availability, mean annual yield, visual symptoms of deficiency, fertilizing during the last 3 years, etc. Soil analysis, at least for basic soil properties and macro-nutrient content Leaf analysis Soil analysis Soil analysis: The knowledge of key soil characteristics is essential for defining the details of a fertilizing schedule. Important parameters are: Soil ph and CaCO 3 content It is important to define the type of fertilizers to be used In soils with ph>7 and adequate CaCO 3 the use of ammonium sulphate is preferable In soils with lower ph and low CaCO 3 the use of fertilizers that do not contribute to soil acidification is preferable (e.g. calcium ammonium nitrate) 28

29 P N K Ca Soil ph effect on nutrient availability Fe Mn S Mg Zn Mo Cu B Soil analysis Soil salinity: Usually, when good quality water is used for irrigation soil salinity levels are <1 ds/m Increased salinity is usually linked to the use of saline irrigation water When soil salinity is high, the use of fertilizers containing Cl (e.g. potassium chloride) is avoided since they may enhance the problem 29

30 Soil analysis Soil texture Coarse textured soils (sandy): Higher losses of nutrient due to leaching Measures like increase of organic matter, application of fertilizers at the end of the raining season, splitting of N application in more doses and fertigation should be considered Fine-textured soils: Elements like K are strongly bound and less available to plants. Higher doses of K, Ca and Mg might be required in order to correct deficiency problems Measures to avoid flooding should be taken, since it results in root damage, stunted growth and nutrient uptake, if it occurs during spring Soil analysis Soil organic matter content High organic matter % can provide significant amounts of N, P and micronutrients and therefore, application of chemical fertilizers should be adjusted accordingly Increasing of soil organic matter is always favourable in improving nutrient availability and reducing losses 30

31 Soil analysis Soil mineral element availability Much more important for annual crops However, it provides useful information concerning the availability of some key macro-nutrients The complexity of mechanisms involved in soil nutrient availability and the antagonistic effects among different nutrients make difficult the prediction of the actual nutrient availability to the plant. Leaf analysis is far more important in determining the existing nutritional problems. Soil sampling Timing Not many restrictions For practical reasons: when soil is wet and before the application of fertilizers Sampling Ideal: use of auger for extracting a soil profile from 5-30 cm In deep soil profiles a second sample beyond 30 cm may be taken, although nutrient uptake is usually taking place in the upper cm 31

32 Soil sampling Sampling For small orchards (up to 0.5 ha) and uniform soil, 1 composite sample per depth is collected When an known or visible soil variability exists, 1 sample for each case is collected, independently from field size In large orchards, it is recommended to take more than 1 samples, independently from soil uniformity Soil sampling Sampling Sampling point: under the tree canopy or in the area where fertilizer is spread. Tree canopy Fertilizer application area Right sampling point X Wrong sampling point 32

33 Soil sampling Sampling In irrigated orchards it is better to sample along the drip line Drip line Soil sampling Sampling points: At least 10 points per sample After mixing about 1 kg is sent for analysis 33

34 Soil analysis interpretation Parameter Values Soil ph Soil texture Medium-textured Total CaCO3 >2% Organic matter content >2% Electr. conductivity <4 ds/m NO3-N mg/kg P mg/kg K (medium soil texture) ~150 mg/kg Ca (medium soil texture) >1000 mg/kg Mg (medium soil texture) ~100 mg/kg Fe >3 mg/kg Zn >0.8 mg/kg Mn >1.4 mg/kg Cu > 0,2 mg/kg B >1 mg/kg Defining mineral nutrient requirements Leaf analysis Defining the mineral nutrient content in leaf tissue is the most important tool to detect nutritional deficiencies, imbalances and toxicities in an olive orchard Using this information, and knowing key soil properties and basic information about the orchard we try to interpret the analysis and detect the source of the problem 34

35 Defining mineral nutrient requirements Sample recording information (Ref. No., Farmer, Location, Contact Information, etc.) Crop and cultivar Tree age Planting density Tree size Visual deficiency symptoms Other important problems Winter fertilizing schedule (last 3 years) Foliar applications or fertigation Irrigated or rainfed Defining mineral nutrient requirements Leaf analysis Detecting the source of nutritional problems Low nutrient availability in soil adding the missing nutrient Antagonism minimize application of another nutrient Wrong application timing optimize timing rather than increase amount Wrong application method adjust (e.g. foliar application instead of soil application) Low uptake due to soil ph adjust (e.g. liming) Disease Disease control 35

36 Defining mineral nutrient requirements Leaf analysis Based on the above, we give information for required modifications, additions or exclusions to the existing fertilizing scheduling Leaf analysis Previous fertilizing schedule Orchard information Leaf analysis Adjusting Fertilizing Soil analysis Select fertilizer type, frequency or method 36

37 Leaf analysis Previous fertilizing schedule Orchard information Leaf analysis Adjusting Fertilizing Soil analysis Select fertilizer type, frequency or method Δείγμα 1 Ε Φ Ν P K Ca Mg Fe Zn Mn Cu Very Low Low Δείγμα 2 Ε Φ Optimum Δείγμα 3 Ε Φ High Δείγμα 4 Ε Φ Excess Δείγμα 5 Ε Φ Δείγμα 6 Ε Φ Δείγμα 7 Ε Φ 37

38 Leaf analysis Sampling time: In all tree crops, leaf nutrient content is changing over time depending on leaf age and plant growth cycle. Therefore, leaf analysis is performed during a period where the content of different elements is the most stable. Moreover, the standards that have been developed also refer to a certain period and not to the whole growing season. Leaf analysis Two possible periods: Summer: Second half of July Winter: Late October - November 38

39 Leaf analysis Period of sampling Summer sampling: + The leaf content is not affected by the fruit load + Fertilizing can be adjusted according to the known expected fruit load - Rainfed trees might already be stressed and therefore nutrient content be affected by water stress and not by nutrient availability - Not enough ways to correct nutrient deficiencies at that period of time in most of the orchards 39

40 Period of sampling Winter sampling: + The tree water status is adequate + The degree of exhaustion is known and measures can be taken in order to avoid key nutrient deficiencies early in the following season - Nutrient content might have been affected more by fruit yield than by nutrient availability in the soil Leaf sampling Leaf age: Leaves from current growth 3-5 months old Sample size: About 200 leaves At least trees. Trees should be representative of the typical situation for the orchard. Selected shoots also representative. Avoid leaves or trees with disease damage or any other distinct symptom and trees at the borders of the orchard Sample taken at human height (middle section of the canopy) 40

41 Leaf sampling Number of samples: 1 sample for each uniform block of soil Different samples if trees of different age, cultivar, management system, etc. are present Sample treatment: Ideally: place in a cool box and transfer to the lab If leaves are not to be transferred soon to the lab, they have to be stored in the refrigerator for short period (1-2 days). Soil and leaf analysis time-frame 1. A soil analysis detects key soil properties and nutrient availability 2. Leaf analysis detects nutritional problems. 3. Leaf analysis is repeated for 1 or 2 years to finalize adjustments. 4. After that, leaf analysis is repeated every 2-3 years 5. Soil analysis is repeated every 5 years 41

42 Proposed values for leaf analysis interpretation (October-November sampling / leaves 5-6 months old). Element Deficiency Low High Excess Nitrogen (%) < >2.2 Phosphorus (%) < >0.15 Potassium (%) < >1.3 Calcium (%) < >2.5 Magnesium (%) < >0.30 Boron (ppm) < >150 Iron (ppm) Zinc (ppm) 5-10 >30 Manganese (ppm) < >150 Copper (ppm) <5 >20 Source: Androulakis I. Proposed values for leaf analysis interpretation (July sampling / leaves 3-5 months old). Element Deficient Toxic Nitrogen (%) Phosphorus (%) Potassium (%) Calcium (%) 0.3 Magnesium (%) 0.08 Boron (ppm) Iron (ppm) Zinc (ppm) Manganese (ppm) Copper (ppm) Source: Fernandez-Escobar

43 Fertilizing olive trees As soon as the nutritional status of the tree and the soil properties are known, a fertilizing scheduling is issued, determining: The timing of application The type of fertilizer to be used The quantity of fertilizers (depending upon the nutrient contant of the selected type) Additional corrective measures to be taken to improve soil fertility, or other properties The optimal application method to be used depending on available means and soil properties Alternative methods to be used Soil application (winter or spring) Fertigation Foliar application Injection 43

44 Soil application - Timing Optimal timing depends upon the climatic conditions of the area Water is a crucial factor (amount and distribution of precipitation) Κ, Ρ, Β: Up to the end of December (Cretan example) Ν fertilizers (Cretan example): Ammonium sulphate: Second half of January Calcium ammonium nitrate: mid-february Ammonium nitrate: Before the last rainfalls Application of ammonium-containing fertilizers should not be followed by extended periods of hot and dry weather Soil application Type of fertilizer In general, it is better to select single-element fertilizers, as compared to compound fertilizers Timing of N vs P or K application is different and therefore optimal timing cannot be achieved by the use of a composite fertilizer Depending on soil ph, different fertilizers have to be used: Alkaline ph and high CaCO 3 Ammonium sulfate Acid ph and low CaCO 3 Calcium ammonium nitrate Salinity and soil texture issues should be considered: Avoid Cl containing fertilizers in soils with high salinity (e.g. KCl) 44

45 Fertilizer labeling example % N 6% P 2 O 5 12% K 2 O Content of additional nutrients is also mentioned Terminology: Fertilizing Unit Examples of single-nutrient fertilizers Nitrogen Ammonium sulfate (21-0-0) Calcium ammonium nitrate (26-0-0) Ammonium nitrate (34-0-0) Urea (46-0-0) Potassium Potassium sulfate (0-0-50) Potassium chloride (0-0-60) K-Mg sulphate (0-0-30) 45

46 Soil application Mechanical Soil application Manual 46

47 Soil application Incorporation to the soil is in general suggested at least for K and P fertilizers However, especially in sloppy areas, the disadvantages of any kind of soil cultivation are more than the advantages of fertilizer incorporation Soil application during spring In areas where there are significant rainfall events during spring, application of N fertilizers could be split in 2 (winter + spring application) Advantages: Lower risk of losses through leaching Nitrogen demand during spring is high Ammonium nitrate is the typical fertilizer used Not applicable in areas where spring is typically dry 47

48 Fertigation and foliar application Apart from application of fertilizers to the soil, foliar application and fertigation are also practiced in olive orchards Both methods have the advantage of targeted application timing that coincides with high demand periods for certain nutrients However, cost of application and lack of means of application lead to limited use in most traditional olive orchards Annual growth cycle Mineral nutrient requirements JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Dormancy Active shoot growth Limited shoot growth Active shoot growth Dormancy Flower. bud differentiation Fruitset Pit hardening Increase of Oil content Fruit growth Fruit color change Flower bud formation Flowering Determination of yield potential Maturation Harvesting Harvesting High demand on nutrient requirements B N K JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 48

49 Fertigation Advantages: Fertilizer is applied in the root zone under favorable soil moisture conditions and therefore nutrient uptake ratio is higher as compared to soil application during winter The nutrient use efficiency is increased Nutrient losses are limited Application can be adjusted according to expected fruit load Disadvantages: Only applicable in irrigated orchards Only applicable under certain irrigation methods Not adequate experimental data exist for most areas and cultivars In problematic soils it may increase soil salinity problems Costs involved Problems in scheduling in areas where water availability is limited Fertigation It can be applied as an exclusive method for nutrient application, or additionally to winter application Data from a summer foliar analysis program could be used in an optimal way at fertigated olive orchards At a higher cost, the application of water and nutrients could be fully automated Application of water and nutrients at high rates could reduce olive oil quality 49

50 Fertigation Nitrogen: If fertigation is exclusively used for fertilizing the orchard, applications should start early in spring, even if there is no need for irrigation Potassium: Higher demands after June Fertigation Not all fertilizers are equally appropriate to be used for fertigation Fertilizer Ammonium nitrate Ammonium sulphate Urea Monoammonium phosphate Diammonium phosphate Potassium chloride Potassium nitrate Potassium sulphate Monopotassium phosphate Phosphoric acid N P2O5 K2O content Solubility (g/l) at 20 C

51 Foliar application Advantages: When soil properties do not favor the uptake of certain nutrients, foliar application can be the most effective way to correct deficiencies Tree response is faster, as compared to soil application An alternative for rainfed orchards in cases of long dry periods that do not favor soil application Foliar application Disadvantages: Application rates are low and therefore macronutrient requirements (N or K) cannot be covered by a single foliar application. Usually applied as a supplementary method Cost may be high to cover macronutrient requirements Not effective for long. It usually covers the annual requirements of micronutrients but should be repeated on an annual basis Rainfall after application may affect the effectiveness 51

52 Foliar application Efficiency of foliar application is affected by several environmental factors: Light, Temperature, Humidity Effects of environmental factors could be: Direct effects on spray solution prior to absorption Indirect effects on leaf development processes Indirect effects on photosynthesis, stomatal opening and sink activity, affecting energy and metabolite availability involved in the uptake process Foliar application Nutrient uptake is higher in young olive leaves as compared to older leaves Not well hydrated leaves (water stressed) uptake less nutrients than fully hydrated leaves. Therefore, spring (preferably) and autumn (if rain occurs) sprays are more effective than summer sprays Avoidance of hot days and application during the cooler part of the day increases absorption Surfactants are used to increase absorption 52

53 Foliar application Foliar application has been effectively used as a supplementary method for applying N or K in olive trees In cases of severe K deficiency trees may respond faster as compared to soil application There are reports suggesting that late spring application of K gave better results than late summer application in olive trees Not effective for Fe application Spring application of Boron may enhance fruit set as compared to untreated olive trees Common compounds used Macronutrient N Common element compounds Urea, ammonium sulphate, ammonium nitrate P H 3 PO 4, KH 2 PO 4, NH 4 H 2 PO 4, Ca(H 2 PO 4 ) 2, phosphites K K 2 SO 4, KCl, KNO 3, K 2 CO 3, KH 2 PO 4 References Zhang et al. (2009); Fageria et al. (2009) Noack et al. (2011); Schreiner (2010); Hossain and Ryu (2009) Lester et al. (2010), Restrepo- Dνaz et al. (2008) Mg MgSO 4, MgCl 2, Mg(NO 3 ) 2 Dordas (2009a), Allen (1960) Ca CaCl 2, Ca-propionate, Caacetate Source: V. Fernandez, T. Sotiropoulos. P. Brown, 2013 Val and Fernαndez (2011); Wojcik et al. (2010); Kraemer et al. (2009a,b) 53

54 Fruit dry weight (g/100 fruit) 24/10/2016 Common compounds used Micronutrient B Fe Common element compounds Boric acid (B(OH) 3 ), Borax (Na 2 B 4 O 7 ), Na-octoborate (Na 2 B 8 O 13 ), B-polyols FeSO 4, Fe(III)-chelates, Fecomplexes (lignosulphonates, glucoheptonates, etc.) References Will et al. (2011); Sarkar et al. (2007), Nyomora et al. (1999) Rodriguez-Lucena et al. (2010a, 2000b); Fernαndez et al. (2008b); Fernαndez and Ebert (2005); Moran (2004) Mn MnSO 4, Mn(II)-chelates Moosavi and Ronaghi (2010), Dordas (2009a), Papadakis et al. (2007), Moran (2004) Zn ZnSO 4, Zn(II)-chelates, ZnO, Zn-organic complexes Source: V. Fernandez, T. Sotiropoulos. P. Brown, 2013 Amiri et al. (2008); Haslett et al. (2001), Moran (2004); Zhang and Brown (1999). Ξηρό βάρος σε gr /100 καρπούς Oct Nov Dec Jan Feb Mar Οκτ-96 Νοε-96 Δεκ-96 Ιαν-97 Φεβ-97 Μαρ-97 Ημερομηνία Date δειγματοληψίας Ουρία Urea 2% 2% Μάρτυρας Control Θειικό K2SO4 Κάλι 2% 2% Effect of autumn N and K foliar application on fruit dry weight 54

55 Flesh d.w./stone d.w. ratio Oil % (d.w.) Urea 2% Control Control K 2 SO 4 2% K 2 SO 4 2% Urea 2% 24/10/2016 2,10 1,90 Ουρία 2% Μάρτυρας Θειικό Καλι 2% Λόγος ξ.β.σάρκας / ξ.β.πυρήνα 1,70 1,50 1,30 1,10 Oct Nov Dec Jan Feb Mar Οκτ-96 Νοε-96 Δεκ-96 Ιαν-97 Φεβ-97 Μαρ-97 Ημερομηνία δειγματοληψίας Date Effect of autumn N and K foliar application on flesh/stone dw ratio Ελαιοπεριεκτικότητα % ξ.ο.τηε σάρκα Μάρτυρες K2SO4 2% Ουρία 2% 50 1/10/1996 Oct 1/11/1996 Nov 1/12/1996 Dec 1/1/1997 1/2/1997 1/3/1997 Jan Feb Mar Ημερομηνία δειγ ματοληψ ίας Date Effect of autumn N and K foliar application on fruit oil percentage (dw) 55

56 HELLENIC AGRICULTURAL ORGANIZATION DEMETER Thank you for your attention Institute of Olive Tree, Subtropical Crops and Viticulture Laboratory of Plant Mineral Nutrition & Physiology