The effects of Fe-chelate type and PH on substrate grown roses

Substrate grown roses appear to be susceptible to chlorosis, which indicates problems with Fe or Mn uptake and hence yield reduction. In common practice this problem is often treated by the addition of extra Fe-chelate, or the use of Fe-EDDHA instead of Fe-DTPA. In previous tests, it was shown that the pH in the root environment is a major factor in the prevention of chlorosis. Moreover, the application of Fe-EDDHA does not always show satisfying improvements in practice. The interaction between Fe-chelate types (EDDHA and DTPA) and pH was studied with roses cv. ‘Kiss’ and ‘Escimo’ on glasswool substrate, reusing drainage water. pH levels compared were about 7, 5.8 and 4.5. The treatments resulted in significant chlorosis and consequently yield reduction at high pH with both cultivars and both chelate types. Highest yields were obtained at low pH, especially with ‘Escimo’. The Fe uptake was clearly affected by the pH with both chelate types. At high pH the Fe-uptake was significantly higher with Fe-EDDHA; however the Mn contents in the plant were significantly lower with these treatments. The uptake of Zn and Cu was also affected by specific combinations of pH and the type of chelate. It was concluded that an optimal pH control was the best method of preventing chlorosis. The choice of the chelate type was less effective and could enhance Mn deficiency

Determination of micro nutrients in substrates by water extraction and interpretation of the analytical data

In 1974 the 1:1½ volume extract was published (Sonneveld et al., 1974) as a water extraction method for the determination of available nutrient elements and of the salinity status of peaty substrates. The analytical data of this extract were related to the data of the “substrate” solution extracted from the substrates with a moisture condition of -3.2 kPa. The method has been widely used and offers a suitable basis for fertilization of peaty substrates. In the years after publication, the composition and application of substrates has undergone much change and the irrigation methods have also been thoroughly adjusted. The latter was responsible for increased water contents in the substrate during crop growth. Therefore, another study was carried out in which the analytical data of the 1:1½ volume extract was compared with the analytical data of the “substrate” solution, where the “substrate” solution was defined at the moisture condition of -1.0 kPa. There was a good agreement between the results of both studies. However, the regression coefficients for the relationships between the data of the extracts differ, as expected, because of the higher moisture contents on which the substrate solution was defined. In addition to the data of major elements published, in the second study, micro nutrients were determined in the extracts, but not published. Therefore in this paper the relationships between the concentrations of micro nutrient as determined in the 1:1½ extract and in the “substrate” solution are given. The relationships presented support the interpretation of analytical data of micro nutrients by means of water extraction

Farm Diversification in Relation to Landscape Properties

Current European Common Agricultural Policy (CAP) has been moving from production support subsidies to direct decoupled income support. The emergence in policy making of the concept of multifunctional agriculture leads to the recognition that a farmer produces more than food: he produces jointly both commodity and non-commodity goods. Environmental contracts were developed in order to encourage the provision of non-commodity goods such as landscape or biodiversity. Next to these contracts, other activities as for example recreation can be observed. They are the result of farm diversification. The role of location in farmers’ decision making to diversify is pointed out in literature but geographical information is generally reduced to the location within a political delimitation unit the empirical work. Objective of this paper is two-fold. Firstly, it addresses the role of location, in term of site specific natural conditions as well as neighbouring emerging dynamics in farmer’s decision making to diversify. Attention is paid to number of activities as well as the specific types of activities, notably green services, daily recreation and other farm-linked services. Secondly, this paper introduces income from agriculture explicitly allowing testing short term price sensitivity. It was found that attractive landscape is a driver for diversification as these landscape offer more opportunities. Furthermore, diversification is responsive to price. Thirdly, role of density of past multifunctional activities in the neighborhood influences farm diversification: multifunctional activities create an externality effects as new activities emerge next to already existing ones. This dynamic may lead to the emergence of ‘multifunctional hotspots’ in landscape.Farmer diversification, landscape services, location, Farm Management, Land Economics/Use,

Nitrogen, potash and magnesium nutrition of some vegetable fruit crops under glass.

Different concentrations and proportions of N, K and Mg were applied as supplementary fertilizers to various crops through the irrigation system (strip spraying). Fertilizer containing 9 mol N, 4 mol K and 1.6 mol Mg/kg applied at electrical conductivities between 0.45 and 0.9 mS/cm at 25 deg C produced yields of up to 15.6, 19.7, 9.5 and 20.2 kg/m2 of tomatoes, cucumbers, sweet peppers and eggplants, respectively. (Abstract retrieved from CAB Abstracts by CABI’s permission

Zout gietwater bij kasteelten in West - Nederland

De glastuinbouwbedrijven in West-Nederland hebben van een hoog zoutgehalte van de grond herhaaldelijk veel nadeel ondervonden. Een dertig jaar geleden had hier de verzouting van de kasgronden de volgende oorzaken: zout gietwater; opstijgend grondwater; onoordeelkundig bemesten. Het zoutgehalte van het gietwater vormt ook thans nog een probleem

De samenstelling van de zouten in het oppervlaktewater in het Zuidhollands glasdistrict

Aan de kwaliteit van het water dat in kassen voor de besproeiing van gewassen wordt gebruikt, dienen hoge eisen te worden gesteld. Zo is bij voorbeeld het gebruik van sproeiwater dat verontreinigd is met pathogène organismen, uit hygiënisch oogpunt niet toelaatbaar. Voorts kan verontreiniging met anorganische verbindingen nadelig zijn en wel vanwege een remmende invloed op de plantegroei of vanwege vervuiling van gewassen en kasopstanden. Bepaalde anorganische stoffen, zoals ijzer, kunnen reeds in lage concentratie - enkele milligrammen per liter - het water ongeschikt maken als sproeiwater