Coffee, fertilizer, and the pursuit of sustainable farming: Understanding edaphic context to improve nutrient management strategies for smallholder coffee production in a volcanically active region

Allen Asensio, Heidi

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https://hdl.handle.net/2142/120428 Copy

Description

Title

Coffee, fertilizer, and the pursuit of sustainable farming: Understanding edaphic context to improve nutrient management strategies for smallholder coffee production in a volcanically active region

Author(s)

Allen Asensio, Heidi

Issue Date

2023-05-02

Director of Research (if dissertation) or Advisor (if thesis)

Margenot, Andrew J

Committee Member(s)

• Villamil, Maria B
• McSweeney, Kevin
• Pulleman, Mirjam

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• coffee
• soil
• nutrient management
• carbon
• fertilizer

Abstract

Coffee (Coffea arabica) is a globally important perennial cash crop that is produced by smallholders in a variety of landscapes across the tropics. The mountainous and volcanically active topography in Central America provides optimal elevations for coffee production, resulting in a diverse land use tapestry dominated by smallholder coffee farms. This study examined the edaphic characteristics, nutrient use efficiency and landscape-specific nutrient management at smallholder coffee farms in a volcanically active region. Understanding the characteristics of soils in this region in concert with evaluating the response of coffee plants to fertilizer input is relevant to prevent the misuse of smallholder financial resources by over- or under-applying certain nutrients. The objectives of this study were to 1) to evaluate the interactive effect of soil formation and coffee-dominated land use on SOC stocks and nutrient vertical distribution and 2) to identify nitrogen (N) and potassium (K) driven coffee yield gaps and quantify nitrogen use efficiency (NUE) and potassium use efficiency (KUE) via on-farm omission trials, in a representative smallholder coffee landscape of Central America located in south-central Guatemala with an active stratovolcano. First, 37 pedons across three land uses were characterized and classified (USDA Soil Taxonomy) to understand how volcanic activity and land use impacted the development of soil properties, soil burial, and SOC and nutrient vertical distribution. Additionally, SOC stocks were calculated with the fixed depth (FD) and equivalent soil mass (ESM) methodologies to evaluate if soil burial would affect the stock estimation. Vulcanism had a strong effect on the development of andic properties and soil horizon burial. Thirty-one pedons were classified as Andisols, three as Inceptisols and three as Entisols. The vertical distribution of SOC concentrations and SOC stocks showed patterns that may be attributed to soil horizon burial by deposition of volcanic material and land use management practices. While the vertical distribution of macronutrient and micronutrients did not reflect the effect of burial, macronutrients were more sensitive to land use differences than micronutrients. Despite SOC stocks being similar when calculated using FD and ESM methodology in this study, the use of the FD approach may be advantageous from a pedological perspective, and the ESM methodology may be more appropriate for the evaluation of SOC over time. After understanding the edaphic context of the landscape, on-farm omission trials were established across 21 fields to test the effect of a single high-rate application of 285 kg ha-1of N and of 350 kg ha-1 of K, singly and in combination, on coffee yield, soil extractable N and K, foliar concentrations of N and K, concentrations of N, P and K of coffee cherries, and yield-based export of N, P and K. While coffee yields, soil extractable N and K and foliar concentrations of N and K were similar among fertilization treatments, field stratification by organic matter (OM) content showed that fields with greater OM overall yielded 2-fold greater compared to low OM fields. Furthermore, tradition al landrace and introgressed coffee varieties had 1.8-fold lower yields than the F1 hybrid H1 Centroamericano. In these coarse textured soils, nutrient loss due to leaching may impair the effectiveness of nutrient input via fertilizer application. Since N, P and K concentration in coffee cherries were found to be relatively constrained, nutrient removal rates can be assumed to scale linearly with cherry yields, enabling facile assessments of nutrient replacement rates. Values of NUE and KUE were not agronomically indicative due to the similarity between yield among treatments. The results of this study show that properties of soils in this region that result from the deposition of volcanic material may be both beneficial and challenging for smallholder coffee production. Stable and abundant organic carbon stabilization by short-range order minerals from the volcanic parent material and the inhibition of organic carbon decomposition by Al-organic complexation may contribute to make OM a source of native fertility. On the other hand, coarse textures facilitate nutrient loss by leaching, thus emphasizing the need for landscape-specific recommendations for nutrient management that are economically sound and scientifically accurate. 

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Heidi Allen Asensio

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