Dynamics of nitrogen availability in pot grown crops with organic fertilization

Abstract

Pot grown herbs are often cultivated as certified organic products, and there is an increasing demand for organically certified ornamental plants. Supplying the required nutrients using organic fertilizers is a challenge with respect to matching the mineralization and thus the availability of dissolved nutrients in the growing medium with plant demand. In experiments, sweet basil and Pelargonium × hortorum were cultivated using two different organic fertilizer strategies and controlled-release mineral nutrients as control treatment. The two organic strategies were, i) blood meal + Baralith® Enslow (a plant-based organic fertilizer), and ii) poultry manure. The availability of dissolved nitrogen was monitored during the crop cycle by under-pressure lysimeter sampling. Plant development parameters were measured along with chlorophyll fluorescence and chlorophyll concentration of leaves. For both organic treatments, nitrate-N availability was low at the beginning of the experiment, whereas ammonium-N was high. During the experiment, ammonium availability decreased at the same time as nitrate availability increased after a few weeks and then declined again by the end of the experiment. The blood meal + Enslow treatment caused poor germination and slow growth in basil. Plant height and fresh weight was also affected by this treatment for basil but not for Pelargonium. Chlorophyll concentration was affected by treatment, with also visually detectable paler leaves in the treatment with poultry manure. There were no differences in chlorophyll fluorescence (F v /F m) between treatments, indicating that plants were not stressed in any of the treatments.

Ammonia and Ammonium Exposure of Basil (Ocimum basilicum L.) Growing in an Organically Fertilized Peat Substrate and Strategies to Mitigate Related Harmful Impacts on Plant Growth

“…Under these conditions, the development of radicle, hypocotyl, and cotyledons was strongly inhibited ( Figure 5B). Similar adverse effects of ammonical N forms on germination and seedling development were reported for several plant species (Bremner and Krogmeier, 1989;Ells et al, 1991;Britto and Kronzucker, 2002;Qi et al, 2012;Bergstrand et al, 2018).…”

“…A study on wheat has shown that the seed germination of this cereal species is unaffected at NH 3 concentration below 0.3 ppm, but completely inhibited at 0.8 ppm (Pairintra, 1973). For pot grown basil, a poor germination and weak plant growth was observed when the NH 4 + -N concentration was between 100-130 mg (L substrate) -1 in the first 3 weeks after sowing (Bergstrand et al, 2018). In contrast, Frerichs et al (2017) reported that the germination process of basil was not adversely affected by NH 4 + -N levels at about 200 mg (L substrate) -1 .…”

“…Lower section of the table: Relationships between plant growth parameters and exposure to mineral N forms as well as substrate pH in the organically fertilized treatments, determined within 7-21 days after sowing, indicated by direction (+/-) and coefficient of determination (R 2 ) for a linear regression model (n = 9). and urea to peat or wood-based substrates (Niemiera et al, 2014;Frerichs et al, 2017;Bergstrand et al, 2018). After adding the amino acid arginine to soil samples, Kemmitt et al (2006) detected the highest NH 4 + concentration 2-8 days later.…”

Biochemical, Physiological and Yield Characteristics of Red Basil as Affected by Cultivar and Fertilization

“…in order to allow the nitrification process starting, thus preventing the initial ammonium accumulation and enhancing the total nitrate amount released to plants over the entire crop cycle. However, the low nitrification rate recorded by Bergstrand et al [38] upon poultry manure application may have been caused by the peat-based substrate, which is sometimes characterized by a faster conversion from organic to ammonium form, compared to the subsequent nitrification [39]. In this respect, the sandy-loam soil used in our investigation has a higher air permeability than the peat substrate, thus increasing the nitrification rate [40].…”

Dynamics of nutrient availability in tomato production with organic fertilisers

“…A study regarding the mineralisation of N for container grown crops has previously been published by the authors of this study (Bergstrand et al 2019). In the study reported here, the focus has been expanded to all essential nutrients and tomato was used as the model crop.…”