Growth ofHedera helixL. Container Plants in Compost Substrates Made withMiscanthus ogiformisHonda Straw and Various N-Sources

Abstract

Ammonium sulfate or urea were added as N-source to shredded straw of Miscanthus ogiformis 'Giganteus' and water was included as control. The combined materials were composted for seven months, and the resulting composts were tested as growth substrates for nursery container plants and compared with fertilized and unfertilized peat substrates. The pH was below recommended level for the compost substrate made with ammonium sulfate and for the unfertilized peat substrate throughout the experiment. Electrical conductivity and concentrations of most nutrients were low and decreased throughout the experiment for all growth substrates. Shrinking of the growth substrates after 4, 12 or 17 months was larger for compost substrates than for peat substrates. Bulk density increased in compost substrates and decreased in peat substrates, while the total loss of C was greater in compost substrates than in peat. Water retention was lower and air volume greater for compost substrate made with ammonium sulfate than for fertilized peat. Algae and mosses did not occur on Miscanthus compost growth substrates in contrast to peat substrates. The shoot length and dry matter of Hedera helix, produced after four and 12 months of growth, and five months following cut back, showed that plants can grow well in compost substrates made of Miscanthus straw and ammonium sulfate or urea. However, the compost substrates could not fully substitute for fertilized or unfertilized peat substrate with respect to dry matter production.

Long-Term Stability and Mineralization Rate Of Compost is Influenced by Timing of Nutrient Application During Composting of Plant Residues

“…In general, roots have the competitive advantage compared to microorganisms as roots grow and is distributed in the medium and thereby can exploit a larger volume for available N. Furthermore, the mere presence of roots would also stabilize the media and compaction would be reduced. Still, some volume loss is expected ranging from 15-50% when using compost based growing media for plants with long production time, although compression of the growing medium in the containers before planting could reduce the volume losses (Jensen et al 2001;Gruda and Schnitzler 2004).…”

“…Amongst others, a low C/N ratio and a high NO 3 -/NH 4 + ratio are often used as maturity parameters (Bernal et al 1998) whereas stability in general is determined by respiration rate, heat development or volume loss. When using compost as a growing medium for containerized plants, stability is furthermore critical as large volume losses should be avoided (Jensen et al 2001;Gruda and Schnitzler 2004). The structure of the material after composting will also affect the volume losses when used as growing medium, as the particle size distribution influences the way the media is compressed by gravity (Gruda and Schnitzler 2004).…”

Nitrogen Immobilisation and Microbial Biomass Build-Up Induced by Miscanthus x giganteus L. Based Fertilisers

“…Moreover, soil potassium (K) status, K + saturation, moisture conditions and the cation exchange capacity of the soil influence the amount of NH 4 + that can be fixed and thus reduce its nitrification and plant availability [76]. Jensen et al (2001) [77] and Leth et al (2001) [78] also conducted composting experiments of Mis with pig slurry and other N sources and observed high microbial activities respectively. Like our experiments, these results indicate a high amount of C in Mis that can be easily degraded by microorganisms, provided that a sufficient amount of available N is accessible.…”

Primary Mechanical Modification to Improve Performance of Miscanthus as Stand-Alone Growing Substrates

“…While stand-alone miscanthus in growbags showed comparable plant yield to control substrate (stone wool) [18,19], increasing the proportion of miscanthus in container substrates leads to decreasing plant growth [9,11,12]. Composted miscanthus could be used as a peat alternative for nursery shrubs, but the performance of tested composts in different plant trials was inconsistent [20][21][22]. Reported challenges of miscanthus substrate include low water holding capacity [9,11], slightly higher pH than the recommended range for soilless crops [8,9,12,14,23], and the risk of nitrogen (N) immobilization [11,12,14,16,23], thus increased substrate shrinkage for longterm cultivation [9,21].…”

“…Composted miscanthus could be used as a peat alternative for nursery shrubs, but the performance of tested composts in different plant trials was inconsistent [20][21][22]. Reported challenges of miscanthus substrate include low water holding capacity [9,11], slightly higher pH than the recommended range for soilless crops [8,9,12,14,23], and the risk of nitrogen (N) immobilization [11,12,14,16,23], thus increased substrate shrinkage for longterm cultivation [9,21]. Appropriate modification strategies to overcome these challenges could determine the adoption of miscanthus in the growing substrate market.…”