Impact of Organic Nutrient Sources and Substrates (Peatlite and Coir) on Organic Transplant Production

Seedlings are sensitive to root zone conditions such as pH, electrical conductivity (EC), aeration and water holding capacity. Organic nutrient sources can affect these conditions and cause fluctuations as nutrients are released. Substrate pH and EC influence germination and seedling growth and ammonia (NH3) volatilization can inhibit germination and damage sensitive seedlings. Several experiments were conducted to examine the effect of fish emulsion, blood meal (BM), feather meal (FM) and pelletized chicken manure (CM) amended coir and peatlite substrates on sunflower (Helianthus annuus), zucchini (Cucurbita pepo var. Black Beauty) and fenugreek (Trigonella) seedling growth. Fish emulsion solution pH and EC increased over a ten day period with varying values at different rates depending on the concentration and initial pH. On day 5, NH3 concentrations of 5 to 10 mg.L -1 volatilized in fish emulsion solutions with concentrations of 0.25, 0.50, 1.00 and 1.50 dS.m-1. With increasing concentrations of fish emulsion, coir pH increased while peatlite pH decreased. There was no significant difference in shoot fresh and dry mass, and leaf area of zucchini seedlings fertilized with fish emulsion concentration of 1.00 dS.m -1 compared to the control treatment. Ammonia volatilization of 5 to 20 mg.L-1 occurred in coir and peatlite amended with BM, FM and CM. These amendments caused pH and EC to increase. Substrates amended with BM had root damage, leaf necrosis and seedling death. The high solubility of CM (26 to 32%), elevated the initial substrate EC values (2.0– 7.3 dS.m-1) as compared to the BM and FM amended substrates. Root damage occurred in the substrates containing a combination of BM and FM. There was no significant difference in shoot and root dry mass of fenugreek seedlings grown in substrates containing BM and CM or FM and CM. However, at the higher rate, there was significant difference and the seedlings developed white necrotic leaves. Coir substrates, incorporated with 6 and 9%, by volume, of chicken manure pellets increased the water holding capacity, while feather meal decreased the water holding capacity but increased the air capacity