Cover Crops for Improving Recalcitrant Soil Organic Matter and Soil Biota Management in Plantain Production Systems in Puerto Rico

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2013: $10,000.00
Projected End Date: 12/31/2016
Region: Southern
State: Puerto Rico
Principal Investigator:
Duamed Colon-Carrion
Agro Tropical, Inc.

Annual Reports


  • Agronomic: sorghum (milo), sugarcane
  • Vegetables: peppers, cucurbits
  • Animals: bees


  • Crop Production: conservation tillage
  • Education and Training: farmer to farmer, on-farm/ranch research, participatory research
  • Energy: energy conservation/efficiency
  • Farm Business Management: farm-to-institution
  • Natural Resources/Environment: carbon sequestration, biodiversity, habitat enhancement
  • Soil Management: green manures, organic matter, soil analysis, soil microbiology, soil quality/health
  • Sustainable Communities: leadership development


    Cover crop treatments (CCs) were planted two weeks after In-vitro plantain plantlets were planted in the field. After 3 months CCs were soil incorporated and replanted. Soil samples were collected to determine SMB, RSOM, and DHA. The major pitfalls on this stage were above normal rainfall (Table 1), poor germination of Crotalaria seeds; and rodent attack to sorghum seeds. This research shows an increase in all these soil health indicators, demonstrating benefits on soil health attributes by using CCs.


    In Puerto Rico (PR), plantain (Musa paradisiaca AAB) production is the main crop industry. It is an intensive high input whose current agronomic affect soil quality (SQ), being recalcitrant soil organic matter (RSOM) and soil biota (SB) reductions some of the principal aspects. The RSOM is the part of soil organic matter (SOM) that resists microbial decomposition. During the investigation it also was decided to consider the measure of labile soil organic matter (LSOM). The LSOM pools can be considered as fine indicators of SQ that influence soil function in specific ways, and much more sensitive to changes in soil management practice (Haynes, 2005). Labile compounds are carbohydrates and proteins; and recalcitrant compounds are mainly lignin, but also suberins, resins, fats and waxes (Rovira, 2002).

    The goal of this project was to improve the SQ by increasing RSOM and SB through the adaptation and implementation of CC to plantain production systems in PR. The cover crops used were Canavalia ensiformis (Jack Bean), Crotalaria juncea (sunnhemp), and Sorghum bicolor (sorghum). In Gurabo, we experience two main problems of poor germination of sunnhemp and sorghum seeds. The sunnhemp is a legume with elevated production of lignin. Due to the high lignin cellulose, and hemicellulose content in the stem, residue will be slow to break down (Sheahan, 2012). Lignin biodegradation is hindered under anaerobic conditions, a common result of waterlogging (Rovira, 2002). With the increase of rain in Gurabo during April, May, and September to December 2016 (Table 1) the incorporation and replanting of the CCs were affected. The soil on the farm is compounded by Caguabo, Juncos and Mabi (Web Soil Survey, USDA). Caguabo is described as well-drained soil but Juncos and Mabi go from moderate to poorly drained soil. These soils combined with the increase of rain in the moment of incorporation and replanting the area affected the degradation of sunnhemp and germination of this and also of sorghum. The most successful CC was the Jack bean with a rapid germination and adaption to sun and shadow conditions that provide the plantain plantation.

    Table 1. Summary of maximum and minimum temperature and total precipitation reported in Gurabo, Puerto Rico during 2015 and 2016.


    Project objectives:

    The objective of this project is the evaluation of cover crop intercropping in a plantain plantation to conserve and promote a healthy soil environment for plantain production. The effectiveness of the cover crop integration to the plantain system is evaluated using the following soil quality indicators: 1) Recalcitrant Soil Organic Matter (RSOM), 2) soil microbial biomass (SMB) and 3) Dehydrogenase activity (DHA).

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.