Sampling

The results of the analytical data of soils and substrates are affected strongly by the method of sampling. The great variation in the chemical properties from spot to spot requires a special procedure to gather a sample that significantly reflects the composition of the soil and the substrate in the greenhouse. Variations in chemical properties of spots in a greenhouse area can be distinguished in systematic and in accidental components. Knowledge about the character of the variability is...

Soil Solution and Uptake of Major Nutrients

Nutrient Uptake Curve Brinjal

Marschner 1997 showed an interesting general model for the uptake of macro nutrients in relation to the external concentration. K, P, NO3 and SO4 are supposed to be adsorbed at relative high quantities at low external concentrations and the uptake of Na, Mg and Ca are much more dependent of the external concentration. Comparable relationships has been found for substrate grown crops like for K and Mg with sweet pepper, eggplant and cucumber grown in rock wool Sonneveld and Voogt, 1985 , K and...

References

In Carson E W ed The Plant Root and Its Environment. University press of Virginia, Charlottesville, VA, 441-481. Barraclough P B 1989. Root growth, macro nutrient uptake dynamics and soil fertility requirements of a high yielding winter oil seed crop. Plant Soil 119, 59-70. Campbell R B Bower C A and Richards L A 1948. Change of electrical conductivity with temperature and the relation of osmotic pressure to electrical conductivity and ion concentration for soil...

Soil Solution and Uptake of Micro Nutrients

The quantities of micro nutrients in soil solutions are small in comparison with those found for major nutrients. In Table 3.6 average concentrations of micro nutrients are shown as has been found in greenhouse soil solutions Sonneveld and De Bes, 1986 and in substrate solutions of rock wool Sonneveld and Van Voorthuizen, 1988 . The concentrations in the different growing media are of the same order of magnitude. Greatest difference has been found for Fe, which will be explained by the use of...

Nutrient Uptake

Despite a precise application and an efficient utilization of nutrients in the modern greenhouse industry, the required additions of nutrients will stay high in this horticultural branch. This is related to the high yields usually gained in greenhouses. Between the yield of crops and the uptake of nutrients often a close linear relationship was found, like shown for tomato and chrysanthemum in Fig. 1.1. The relationships shown for both crops differ strongly. This can be explained by several...

Changes in the Chemical Composition

The chemical composition of soil solutions will change strongly, mainly by factors like nutrient uptake by crops, leaching of nutrients by irrigation and supply of nutrients by fertilization. The grower often switches the concentrations of specific ions as well as the total ion concentration EC deliberating the requirements of the crop. For some crops the EC is increased strongly like at the start of fruit vegetable crops to promote an early fruit setting and to prevent a lush growth, as...

Symptoms of Nutrient Disorders

Symptoms of nutrient disorders in greenhouse crops do not differ in principle from those in field crops. Most of the characteristics of nutrient disorders found with field crops also occur in greenhouse crops. So there is no reason for an extended description of these symptoms. However, the specific climatic conditions in greenhouses sometimes induce symptoms accompanied by specific characteristics. Therefore, a short description will be given of the most characteristic symptoms of the nutrient...

Organic Fertilizers

Organic fertilizers are produced from animal or plant material and are for that reason popular in the organic horticulture. They are sometimes used for traditional soil grown crops and to some extent as an amendment in organic substrates. There is a broad variety of source, some of these fertilizers are prepared from single Fig. 2.2 Release of N from 35 industry in an incubation 30 soil in comparison with 25 Proefstation, 1954 J 20 0 10 20 30 40 50 60 Days after addition protein-like materials...

Fertilization Programmes

In the past fertilization and irrigation in greenhouses was based on the experiences of growers. The addition of farm yard manure and other natural organic products was common practice, supplemented with fertilizers used for field crops. Often these fertilizers contained high NaCl contents. Formerly, this was mostly not a problem for field crops, because of the surplus of the precipitation in winter, by which the salt residues were leached from the root zone. However, since the natural...

Fertilizers

In this section a review will be given of the fertilizers commonly used in greenhouse horticulture. The choice of the fertilizer types used in greenhouse industry sometimes differs from those for field crops, because of the fact that the choice for field crops is strongly determined by the price of the fertilizer. This scarcely is a factor in the greenhouse industry, because fertilizer costs represent only a minor fraction of the total costs of greenhouse industry. The characteristics on which...

Introduction

Tissue tests are widely used in horticulture practice and have in comparison with soil or substrate testing advantages as well disadvantages in comparison with soil testing. One of the main advantages of tissue tests is the certainty that analysed nutrients in plant tissues are really present in the tissue analysed, while analytical data of soil and substrate testing only estimate the availability of nutrients to plants. There is no guarantee that nutrients determined in the root environment as...

Interpretation

As already discussed, results of tissue test in greenhouse horticulture are mainly used as a confirmation of nutrient disorders in plants. Incidentally it also is used as a quick test to determine the plant nutrient status to control fertilizer application. However, interpretations of tissue tests are fairly complicated, because they are not unequivocal. Great differences occur between the requirements for optimum production, and for deficient and toxic levels of plant nutrients of different...

Greenhouse Soils In Situ

For a wide range of soil types Van den Ende 1988a found a close linear relationship between the water content of greenhouse soils cultivated with tomatoes and the water content at a pressure head of -6.3 kPa, as shown with formula 3.3 . Wf 1.047W-6.3 - 0.012 r 0.987 3.3 wf mass ratio water solid phase of field moist soil w-6.3 mass ratio water solid phase of soil at a pressure head of - 6.3 kPa Thus, the water contents of the greenhouse soils grown with tomato were more or less equal to that at...

Osmotic Potentials of Soil Solutions

In Table 3.1 the composition of soil solutions from field soils is given in comparison with those from greenhouse industry. In the comparison soil solutions as well as substrate solutions are taken into account. The most striking difference between the solutions derived from fields soils and those from greenhouses soils are the overall much higher nutrient concentrations in solutions from greenhouse. This especially holds for greenhouse soils where the EC in the solution is highest....

Saturation Extract

The saturation extract is prepared by filtration of a water saturated soil. Saturated soil is prepared by addition of demineralised water to field moist soil under continuous stirring with a spatula Richards, 1954 . The saturated condition is assessed by the glistening appearance of the soil paste if it reflects light and by the rapid disappearance of a diametrical groove drawn with the spatula. The use of field moist soil for the preparation of the saturated paste is preferred to air dry soil,...

Specific by Volume Water Extract

Soil Extraction Sonneveld

The specific 1 2 by volume extract, henceforth called 1 2 extract, is prepared by filtration of a suspension obtained by adding sufficient field-moist soil to two volume parts of water so that the total volume is increased with one part Sonneveld et al., 1990 , see picture 4.1. When the soil is too dry, before the preparation of the extract some demineralised water will be added to the soil to restore field moist condition. The field moist condition of greenhouse soils is defined in Section 3.3...

Micro Nutrients

In substrate cultivation the application of micronutrients is common practice, because most growing media has very low contents of minerals. Moreover, when they are available in the growing media the quantity of growing media is small and is possibly soon depleted by the crop. For soil grown crops the application is mostly not necessary, because most soils contain sufficient quantities of these elements to supply the crops. Some are available from natural origin, while others are brought in...

Variations of Uptake and Supply

Many different irrigation systems are available in the greenhouse industry. They can be globally distinguished in following groups. Systems due to spot or strip irrigation, like drip irrigation systems and mini sprinklers. This group is characterized by local wet spots or strips in the greenhouse where the water is supplied, while the remaining part of the surface stays dry. The crop is not wetted during irrigation Van den Ende and De Graaf, 1974 . Systems with which the whole area of the...

Fertilization in Greenhouse Industry

In contrary of many other agricultural activities the costs of fertilization in the greenhouse industry are relatively low and amount to only a few percentages of the total costs. Thus, from economic view points were no arguments for a precise and careful application of plant nutrients. In the past an abundant use of fertilizers in the greenhouse industry was common practice and there was no interest by the growers to limitations in the use of fertilizers to prevent in this way the leaching of...

Bemestingsadviesbasis Grond

Die CaCl2 DTPA-Methode zur Untersuchung G rtnerischer Erden auf Mengen- und Spurenelemente. Agribiol. Res. 45, 204-214. Carpena O Guill n M G Fernandez F G and Caro M 1968. Saline soil classification using the 1 5 aqueous extract. 9th International Congress of Soil Science, Transactions vol. 1, 483-490. CEN 1999a. European Committee for Standardisation CEN TC 223. Soil improvers and growing media - Sampling. EN 12579, 11 pp. CEN 1999b. European Committee for...

Water Quality

The quality of the irrigation water with respect to the mineral composition affects the water supply. When the concentration of any mineral is higher than the uptake concentration, the residual salt accumulates in the root environment and will be Picture 6.2 A basin for storage of rain water leached by extra water supply. Na and Cl are the ions often abundantly present in water, but sparingly absorbed by most greenhouse crops. Therefore, these ions often determine the leaching requirements....