Temperature and moisture effects on CO₂ efflux and nutrient content of incubated soil samples from organic tomato crops

Steeve Pepin¹, Martine Dorais², Carole Boily¹, Claudine Ménard² and Caroline Halde¹

Abstract
The turnover of organic amendments may be a limiting factor for optimal productivity and product quality in organically-grown protected crops. A better understanding of mineralization processes under greenhouse conditions is crucial for optimizing crop nutrient supply, while minimizing losses to the environment.

In this study, we examined the mineralization potential of several organic greenhouse soils maintained at two temperatures (17°C, 23°C) and water potentials (–3.5, –25 kPa). Replicate 196-cm³ soil cores of structurally intact soils (0–10 cm depth) were sampled in plastic cylinders (5 cm ID, 10 cm height; five destructive samplings), saturated with water and adjusted to the appropriate matric potential. Additional soil samples (60 cm³) were screened through a 6-mm sieve, placed in sealed jars and incubated under the same treatment conditions. Soil nutrients, gas content and microbial activity were measured over 25 weeks during aerobic incubation (4 to 8-week intervals).

Large variations in nutrient content were observed among intact soils, and between soil organic matter content. CO₂ efflux declined exponentially with time, decreases being most apparent at high temperature and in soils having high organic matter content. These findings will be discussed in terms of best irrigation strategy to optimize gas diffusion and enhance soil activity.


Source
2007 Guelph Organic Conference, Natural Sciences Symposium


Author Locations & Affiliations
(1) Horticulture Research Centre, Département des sols et de génie agroalimentaire, Laval University, QC, Canada, G1K 7P4
(2) Agriculture and Agri-Food Canada, Envirotron bldg, Laval University, QC, Canada, G1K 7P4


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Posted February 2007