Sustainable Agriculture
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There are many ways to define what it means to be sustainable. There is increased demand for agricultural production transparency to ensure that food and fiber products are being produced sustainably. To this end, Field to Market: Alliance for Sustainable Agriculture has developed the Fieldprint Calculator through the Fieldprint Platform to help farmers of major commodity crops measure their on-farm sustainability by entering in their yearly management practices. This Extension publication defines sustainability, describes the use of the Fieldprint Calculator, and explains how growers can use this program to measure sustainable progress made on their farms. This publication was produced in collaboration with the University of Tennessee and Field to Market.
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Best Management Practices (BMPs) can be described as management and/or structural practices that are designed to reduce pollutants and erosion while increasing the quality of all life. The BMP concept deals specifically with nonpoint source pollution, such as runoff from agricultural fields, forest areas or urban areas. BMPs are also voluntary in nature. Individual practices and applications can vary widely from field to field. Best management practices are typically used in agricultural areas, and forest and urban settings.
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Additional author: Mengmeng Gu, Professor, Colorado State University Department of Horticulture and Landscape Architecture.
Biochar has been proposed to be beneficial to the environment and plants. However, many people do not know what biochar is, what can biochar do, or how biochar can be used. In Part 1 of this publication, we provide introductory information on biochar used to partially replace peat moss as a container substrate component.
The International Biochar Initiative defines biochar as a solid material obtained from the carbonization of biomass, which may be added to soil to improve soil functions and reduce emissions from biomass that would otherwise naturally degrade to a greenhouse gas. Other researchers define biochar as a multifunctional material related to carbon sequestration, greenhouse gas reduction, soil contaminant immobilization, soil fertilization, and water filtration.
To simplify things, we’ll adopt the most popular definition: biochar is a black, carbon-enriched solid with a porous structure, mainly used in agriculture and environmental industries. Biochar is normally made from the thermal decomposition of biomass materials at high temperatures (570–2200 °F) in a low-oxygen or no-oxygen environment (this process is also known as pyrolysis). Biochar can be produced from pyrolysis of different materials such as pine bark, sugarcane bagasse, rice hull, and straw.|
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C 1292-02
Biochar Basics: Effects on Plant Growth
Additional author: Mengmeng Gu, Professor, Colorado State University Department of Horticulture and Landscape Architecture.
Is Biochar Good or Bad for Plant Growth? Mixing biochar into soilless substrates may have negative, zero, or positive effects on plant growth.
Biochar made from green waste mixed with peat at 50% by volume has been shown to increase prayer plants’ total biomass and leaf surface. Adding 10% by volume of sewage sludge biochar with peat-based substrates can increase lettuce biomass by 184%–270%. Mixing pruning-waste biochar with peat-based substrates at 50% or 75% by volume can also increase lettuce biomass. Mixing 20% or 35% (weight per weight) of coir biochar with 0.5% or 0.7% humic acid into a composted green-waste medium showed increased biomass of rattlesnake plants compared to those without biochar and humic acid amendments.
Mixed hardwood biochar (50% by volume) and sugarcane bagasse biochar at 50% or 70% with a bark-based substrate increased basil plants’ average root diameter. Mixed hardwood biochar at 20%–80% by volume increased photosynthesis, shoot fresh weight, and shoot dry weight of chocolate mint, peppermint, Kentucky Colonel mint, spearmint, and orange mint plants. Also, pinewood biochar mixed with pine bark increased chrysanthemum shoot fresh and dry weights.
Biochar may also have adverse effects on plant growth. For example, we tested one type of biochar with high salinity; plants grown in the biochar mixes wilted within 30 min. When plants do not have enough water to dissolve the extra salts, they die.|
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C 1292-03
Biochar Basics: Effects on Plant Disease
Additional author: Mengmeng Gu, Professor, Colorado State University Department of Horticulture and Landscape Architecture.
How does biochar play a role in a plant-disease system? Briefly, before the pathogen infects plants, biochar can improve plant growth by increasing water and nutrient uptake, a healthier plant may be more resistant to attack. On the other hand, after a pathogen infects the plants, biochar could absorb the toxins, enzymes, and other compounds produced by pathogens.
Certain types of biochar could contain chemical compounds which is bad for pathogen growth. When incorporating this biochar into the substrate, the growth environment may become toxic to pathogens, so they cannot grow well enough to attack plants. For instance, eucalyptus biochar water extracts were found to inhibit Pythium growth in a lab setting. This finding indicates that substrate containing certain chemical extracts may impede plant infection by inhibiting the growth of Pythium (Bonanomi et al., 2015). After a pathogen infects a plant, biochar’s porous structure can absorb the toxins, enzymes, and other compounds produced by pathogens. Many types of biochar can improve plant growth, making the host plant stronger to fight against pathogens, thus reducing disease occurrence.|
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Additional author: Mengmeng Gu, Professor, Colorado State University Department of Horticulture and Landscape Architecture.
Container substrates must fulfill several functions for plant growth: create a suitable environment for root growth, physically support them, hold nutrients and water, and enable gas exchange between the roots and the atmosphere. Suitable physical and chemical container substrates’ properties facilitate these functions.
The physical properties of container substrates include air space (%), container capacity (%), total porosity (%), bulk density (g/cm3), and water holding capacity. Air space measures the proportion of air-filled large pores (macrospores) after drainage. Air space influences gas exchange and water holding capacity. Container capacity measures the maximum percentage volume of water a substrate can hold after drainage. Total porosity equals container capacity plus air space, and it measures the substrate volume that holds water and air. Bulk density measures how much one unit of the substrate weighs. Water holding capacity measures the container substrate’s ability to physically hold water against gravity; its maximum value equals container capacity.
Biochar can be derived from various feedstocks, processed under different pyrolysis temperatures, and subjected to various pre- or posttreatments, which can lead to dissimilar physical properties that affect the container substrate’s physical properties. Adding biochar may affect air space, container capacity, total porosity, and bulk density with variable effects. For instance, substituting peat moss with 50% green waste biochar (by volume) did not affect total porosity and container capacity, but significantly decreased air space, which was still in the optimal range (15%–30%) for container substrates. Similarly, a peat-moss-based substrate’s total porosity decreased with the increased addition of pelleted biochar. However, adding deinking sludge biochar increased the total porosity and air space of the container substrate.|
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Label terms and certifications can be divided into those that are regulated and those that are unregulated. Regulated label terms and certifications are usually defined by the United States Department of Agriculture (USDA) or the Food and Drug Administration (FDA). Within the USDA, the Food Safety and Inspection Service (FSIS) is the agency responsible for the truthful labeling of meat and poultry products. The use of labels and certifications is governed by law and violations of use can have legal consequences. Unregulated terms have generally accepted definitions but do not have legal ramifications or verification of adherence. Many common label claims, such as “humanely raised” or “sustainably farmed,” refer to the process used to farm livestock but are unregulated, and there are no legal definitions for these claims. This publication summarizes some common regulated and unregulated terms in agriculture and livestock production.
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Composting is the controlled biological process of decomposition and recycling of organic material into a humus-rich soil amendment known as compost. Mixed organic materials such as manure, yard trimmings, food waste and biosolids must go through a controlled heat process before they can be used as high quality, biologically stable and mature compost (otherwise it is just mulch, manure or byproduct). Compost has a variety of uses and is known to improve soil quality and productivity as well as prevent and control erosion.
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Conservation tillage with agronomic crops (i.e., cotton, corn, soybeans, etc.) has been successful in Georgia production. Such production practices have several benefits, the most notable being the elimination of soil erosion. Other benefits include but aren’t limited to increases in soil organic matter, maintaining a healthy rhizosphere (root-zone soil), reduction of riparian and waterway pollution, and water conservation.
Some examples of conservation tillage practices include no till, ridge till, and strip till. No–till production involves no tillage of field soils and leaves all of the previous crop residue on the soil surface. Ridge–till production involves building a ridge during cultivation, then scalping the ridge and sowing seed. The scalping process moves most of the previous–crop residue to the row middles, leaving a clean row for sowing. Strip–till production is when a narrow strip is tilled for each row that will be planted, leaving the row middles intact with the previous–crop residue. Strip–tillage may reduce yields if weeds in the untilled area are not killed, as these weeds will compete with the crop for water and nutrients. Although the planted row is free of previous crop residue, it may be advantageous to kill the cover crop to prevent it from competing for nutrients and water with the vegetable crop.
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