Many organic growers utilize a preceding cover crop or diverse types of organic fertilizer materials for fertility management. Cover crops are one of the most economical sources of organic nitrogen and provide additional potential benefits for succeeding crops. Time or market constraints and the need to intensively farm high value land may limit the use of cover crops and increase the need to utilize organic fertilizer sources of plant nutrients.
There is a wide array of general guidelines on organic fertilization available in many texts. Many studies conducted over the years with fresh and aged manure are the basis for many of the organic fertilization guidelines. Compost and the different types of commercially available organic fertilizers are very different from manure, and little information is available on their effect on soil nitrogen dynamics and vegetable crop yield.
Compost is often the most economical source of pre-plant applied nitrogen but other organic fertilizer sources may be more convenient for subsequent side dress or fertigation application. Depending upon the composition of the compost there other factors (e.g boron content) which may limit continuous application of compost as a sole source of nitrogen. Several types of commercially available nitrogen fertilizer materials are approved for organic certification but little information exists on optimal management of these materials. Little data has been collected comparing different organic fertilizer materials and different modes of application of these materials for diverse vegetable crops.
Nitrogen (N) nutrient management is often especially critical for optimum yield and quality of organically grown vegetable crops. There are numerous organic fertilizer materials available and the effective and economical use of these materials is important to organic producers, Little information is available on the optimum form and timing of application of different organic nitrogen fertilizer sources. The cost per unit nitrogen of these materials can vary widely - from approximately $1 per pound of nitrogen for compost materials to $51 per pound of nitrogen for some liquid organic fertilizers. Greater than 50 fold differences in price per unit nitrogen are quoted for different organic fertilizer materials from commercial supply sources.
This study was designed to collect critically needed data on soil nitrogen and vegetable crop response following application of different rates and types of commercially available organic fertilizer materials.
We sought to develop scientific data on soil nitrogen dynamics and bell pepper yield in response to the application of different types of commercially available organic nitrogen fertilizer materials. We conducted the trials on bell peppers, a long-term annual vegetable crop requiring repeated fertilizer application. We compared different rates of pre-plant incorporated application combined with varying additional amounts of side banded, incorporated application. We measured weekly soil nitrate nitrogen (SNN), plant tissue nitrogen, and bell pepper fruit yield associated with the different types of organic fertilizers at different application rates.