Nutrient Management Using Compost in Organic Bell Pepper Production

Open Access
Author:
Cook, Emily Klamberg
Graduate Program:
Horticulture
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 01, 2013
Committee Members:
  • Elsa Selina Sanchez, Thesis Advisor/Co-Advisor
Keywords:
  • compost
  • organic
  • nutrient management
  • bell pepper
Abstract:
Fertility management in organic vegetable production systems relies on the use of non- synthetic sources such as compost, manure, and approved fertilizers. Compost is a main source of nutrients on many organic farms. Application recommendations for the use of compost are difficult to make because of the wide variety of feedstocks used in producing compost, and the variable effects of weather, soil type, soil microbial communities and management practices on nutrient release. This research investigates the use of compost as a nutrient source for green bell pepper production. Green bell peppers were grown in two years, using three composts: manure-food waste compost (MFWC), leaf compost (LFC), and spent mushroom compost (SMC). The MFWC was applied at a low rate (10-13 ton/acre) and high rate (20 ton/acre). The LFC was applied at rates to meet pepper nitrogen demand (53 and 65 ton/acre), and the SMC was applied at 15 and 18 ton/acre. Soil tests were taken before compost application and at the end of the season to investigate changes in soil properties and nutrient levels. Leaf tissue analysis and pre-sidedress nitrogen testing were used to monitor in-season nutrient status. Treatment related differences in pepper yield, soil properties and soil nutrients were found in the first year, but not the second. Year related factors were thought to have effected mineralization of composts and plant performance in the second year. Soil nutrient levels were high before compost application in all treatment plots. Applying compost to soils with high nutrient levels is unlikely to result in yield and soil differences after only one season. Soil nitrate was below the suggested 25 mg/kg following application of some treatments over the two years of the study, but crop leaf nitrogen was normal to excessive in all treatment samples, including the unamended control. Nitrate sufficiency levels for pepper production using black plastic mulch may be lower than levels necessary for bare ground production. This study highlights the importance of compost testing for the proper application of the material, and should be regarded in combination with soil tests to determine if there are existing soil problems that would be compounded, or improved, by the application of a particular compost. Pumpkins grown the second year of the experiment, in the same plots as the first year peppers- with no additional nutrient amendments- had poor yields but adequate soil and leaf fertility. Insect and disease pressure were high, and yields were poor in all plots including the control.