Plant growth and soil fertility comparisons of the long-term vegetable production experiment: Conventional versus compost-amended soils

A comparative study from paired compost organic and conventionally-fertiliz ed vegetable plots has been conducted for 10 years in a sandy loam soil nea r Truro, Nova Scotia. The fertility treatments have been applied annually t o rotation plots planted with six to eight different vegetable crops. Compo st and fertilizer applications have been based on the results of soil sampl es and the Nova Scotia Soil Test Recommendations, assuming 50% or 100% avai lability of the total N in the mature composts and fertilizers. The compost s have been made using combinations of animal manure, food waste, yard wast e and straw or racetrack manure bedding. Marketable yields have been taken annually since 1990, while plant tissue samples have been analysed for macr o- and micronutrients. Soils have been sampled for pH, organic matter and M ehlich-3-extractable nutrients since 1994. This paper reports the results o f the 1997 and 1998 cropping years. Crop yields were equal or below normal in 1997 and yields were not consiste nt in response to the two amendments. However, 1998 was a good growing year ; except for tomatoes and broccoli, yields were higher in the compost-amend ed plots compared with the conventional plots. In both years the quality of the carrots was better in the compost-amended plot compared with the ferti lizer plot, which confirms the results of a previous report. In 1997, excep t for Ca and Rig (higher in organic) and K (higher in conventional), tissue results were variable. Comparisons between amended plots in tissue nutrien t content were crop-dependent in 1998; no elements, except Mn (higher in co nventional), were significantly different in leaf tissue content due to fer tility source. Analysis of the soils sampled in the fall of 1998 indicated that Mehlich-3-extractable Ca, pH and organic C were higher in the compost- amended soils compared with the conventional plots. This study is expected to continue for two more years with more emphasis on soil chemical and bioc hemical changes which may have occurred from continuous agronomic applicati ons of compost or fertilizer.