Nitrogen Availability from High-nitrogen-containing Organic Fertilizers

Abstract

<jats:p>Limited soil nitrogen (N) availability is a common problem in organic vegetable production that often necessitates in-season fertilization. The rate of net nitrogen mineralization (N<jats:sub>min</jats:sub>) from four organic fertilizers (seabird guano, hydrolyzed fish powder, feather meal, and blood meal) containing between 11.7% and 15.8% N was compared in a laboratory incubation. The fertilizers were mixed with soil from a field under organic management and incubated aerobically at constant moisture at 10, 15, 20, and 25 °C. N<jats:sub>min</jats:sub> was determined on samples extracted after 1, 2, 4, and 8 weeks. Rapid N<jats:sub>min</jats:sub> was observed from all fertilizers at all temperatures; within 2 weeks between 47% and 60% of organic N had been mineralized. Temperature had only modest effects, with 8-week N<jats:sub>min</jats:sub> averaging 56% and 66% across fertilizers at 10 and 25 °C, respectively. Across temperatures, 8-week N<jats:sub>min</jats:sub> averaged 60%, 61%, 62%, and 66% for feather meal, seabird guano, fish powder, and blood meal, respectively. Cost per unit of available N (mineralized N + initial inorganic N) varied widely among fertilizers, with feather meal the least and fish powder the most expensive.</jats:p>

Comparison of Soybean, Canola, and Mustard Meals as Organic Sources of Nitrogen for Potatoes in Northern New England

“…The three meals had an average N replacement value of 129 lb/acre; (equivalent to 86% of the N present in the meal at time of application) with no significant differences observed among the three seed meals in comparison to each other (individual means for N replacement value were: soybean, 76%; canola, 84%; mustard, 97%; pooled analysis CV = 35.6%). These rates are slightly greater than rates of N mineralization reported for feather meal, blood meal, or bird guano (on the order of 60% to 80% mineralization after 8 weeks) reported from lab studies (4,5). The values from the field study may be greater than those observed in the lab studies due to the longer period involved for mineralization to take place.…”

“…Compost is one potential source of N, however, it is variable depending on its source, and its effectiveness is limited by its relatively slow rate of mineralization (6,12). Work with high‐N containing organic fertilizers, such as blood and feather meal, has shown that these materials can release N in a timely manner for crop production (> 50% N mineralization within 8 weeks of application) (5). Research with teff ( Eragrostis tef ) has shown that mustard seed meal also has potential as an organic source of N (1).…”

Advances and Trends in Organic Fruit and Vegetable Farming Research

“…Nevertheless, most perennial organic fruit production systems use strips of vegetation, such as legumes or cover crop mixes, in the alleys. In practice, the lack of economic justification for using cover crops when the land has a high value and when markets offer a price premium for organic vegetables may limit growers' use of cover crops as well as 4-year rotation systems Hartz and Johnstone 2006), despite that loss of long-term benefit may be observed.…”

“…The C:N ratio of an amendment nutrient source is a robust indicator of potential N mineralization (Gale et al 2006), although mineralization and plant availability will vary according to soil incorporation or surface application, irrigation method used (Neilsen et al 2009), and soil health status. However, it can be considered that 47-60% of the organic N in blood meal, feather meal, guano, and fish powder is mineralized within 2 weeks, and up to 74% is mineralized after 8 weeks (Hartz and Johnstone 2006). For Tithonia diversifolia green manure, 50% of its N content is released within 1 week, and 80% of its N and P contents are released within 3 weeks (Gachengo et al 1998;Jama et al 2000;Ikerra et al 2006;Partey et al 2011).…”

Effect of Organic and Synthetic Fertilizers on the Crop Yield and Macronutrients Contents in Soil and Pepper

“…N is an especially limiting factor for crop growth on organic farms, because the organic N is not readily available to plants and needs to be transformed to dissolved inorganic forms (Gaskell and Smith 2007;Hartz and Johnstone 2006). In conventional farming, inorganic N is supplied by inorganic dissolved salts, which avoids the problem.…”