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Fertilisation management for organic cucumber grown in raised demarcated beds

Dorais, M., Theriault, M., Pepin, S., Lefort, J.
Acta horticulturae 2016 no.1137 pp. 27-32
Eruca vesicaria subsp. sativa, Trifolium pratense, arugula, coir, cucumbers, electrical conductivity, experimental design, fertilizers, fluorescein diacetate, fruit quality, fruit yield, greenhouses, growers, hydrolysis, labor, leaching, live mulches, microbial activity, mulching, nutrient availability, nutrient content, nutrient uptake, nutrients, organic foods, plant growth, plastic film mulches, soil, Quebec
One of the main challenges in production of greenhouse organic vegetables is to achieve a balanced nutrient composition of organic amendments and a timely nutrient release with plant nutrient uptake that will insure high productivity and limit any leaching or emission into the environment. Since the soil should provide the main portion of nutriments to the plant, solid fertilizers are regularly supplied. However, little is known about the fertilisation management of organic greenhouse vegetables grown in raised demarcated beds where root development is confined. The goal of this study was to determine the effect of mulches and the fertilisation frequency on plant nutrient availability and cucumber plant productivity. Two experiments were conducted at Les Serres Lefort located at Ste-Clotilde-de-Napierville, QC, Canada (45°14'N; 73°66'W). In the first experiment, four mulch treatments were compared: 1) plastic mulch, 2) coir mulch, 3) white and red clover, and 4) arugula (Eruca sativa) living mulches. In the second experiment, fertilizers were applied every 1) week, 2) two weeks, 3) three weeks, and 4) four weeks. The same total amount of nutrients was given for each treatment based on plant nutrient uptake. The experimental design was a 4×4 Latin square with 43 to 53 plants per experimental unit. Results showed that the soil electrical conductivity (EC) was higher when a clover and arugula living mulches were used compared to coir mulch. However, soil microbial activity, assessed by the fluorescein diacetate hydrolysis method, was higher under the plastic mulch and lower under the clover living mulch treatment (p=0.052). Nevertheless, no significant difference between mulch treatments was observed for plant growth parameters, fruit size, yield and fruit quality. During the second experiment, the weekly fertilization frequency treatment had generally a lower soil EC compared to the other treatments. Soil microbial activity was slightly higher when fertilizers were given weekly, although no significant difference was observed. Noteworthy, no significant difference was observed for plant growth parameters, fruit size, fruit yield and fruit quality. It can be concluded that on a short-term basis, there was no positive effect of using living mulches compared to plastic mulch used by growers. A 4-week fertilization interval reduced the labour required for the amendment application without any negative effect on plant growth, productivity and fruit quality.