Effect of Nitration of Organic Materials on Nitrogen Availability and Yield of Tomato in Soilless Culture

Abstract

SummaryIn the cultivation of horticultural plants in greenhouses the most commonly used substrate is rockwool, while organic substrates are used in an unprocessed state. Cultivation in organic substrates, after they have been suitably processed, also makes it possible to obtain high yields at levels similar to those in rockwool cultures. Fibrous organic substrates, due to the wide C:N ratio, are characterized by high biological sorption towards nitrogen, causing N deficiency during the initial period of plant growth. In 2007-2009, a study was conducted, the aim of which was to determine the effect of nitration of fibrous organic substrates (sawdust, rye straw, flax shives) with nitric acid on nitrogen availability and the yields produced by tomato plants. The process of nitration of the organic substrates was carried out with the use of 10% HNO 3 . The appropriate pH of the substrates after the process of nitration was obtained by washing the substrates with water. As a result of nitration the levels of nitrogen fixed in lignin compounds and simpler polysaccharides increased to about 2%. Nitration of the organic substrates increased nitrogen availability to plants in the first five weeks of culture. Subsequently, the N-NO 3 content in the nutrient solution collected from the nitrated substrates was at the same level as for the nonnitrated substrates. The yields produced by tomato plants depended on both the nature of the substrate and whether or not it had been nitrated with nitric acid. The most useful organic substrate for soilless culture, retaining good structure during the growing period, was the substrate of sawdust. The substrate of straw was found to undergo quick biodegradation, therefore its usefulness for soilless culture was low. The highest yield of tomato was obtained from the cultures on rockwool and on the nitrated sawdust substrate; the lowest yield was produced on the straw substrate.

Nitric acid-alkali two-stage pulping of wheat straw, industrial hemp, and Miscanthus x giganteus

“…It seems that such filtrates could be used as fertilizer in horticulture, e.g., for soilless cultivation of vegetables in greenhouses on various types of growing media (e.g., Rockwood or Gordan-Master mineral wool). The content of fertilizing elements in filtrates from HNO3/KOH pulping of WS is higher or similar to the content of N−NO3 nitrogen and of K in the nutrient solution used in this type of crop for fertilizing tomatoes, amounting to 200 to 250 mg/dm 3 and 280 to 380 mg/dm 3 , respectively (Kaniszewski et al 2010) and the content of N-NO3, N-NH4, and K in the root zone of plants cultivated with this method, amounting to 400 to 600 mg/dm 3 , 0 to 60 mg/dm 3 , and 300 to 800 mg/dm 3 (Dyśko et al 2012).…”

Agro-industrial-residues as potting media: physicochemical and biological characters and their influence on plant growth

“…Similarly, Vandcasttele et al [ 84 ] reported that reed straw, miscanthus straw, and flax shives have a comparatively high risk of N immobilization compared to peat. There are several strategies to overcome this N immobilization, such as the addition of N fertilizers, treatment with N-containing acid (HNO 3 ) [ 174 ], shifting the pH from the optimal range of microbes, etc. [ 84 ].…”

“…[ 84 ]. Also, nitration of plant fibers (saw dust, flax shives, rye straw) with nitric acid enhanced the availability of N [ 174 ].…”