Commercial Soil
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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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Your goal as a greenhouse grower is to maintain a stable pH over the life of the crop. This is not an easy task since many factors can affect pH in the growing substrate. The pH can go up or down within several weeks of the crop cycle and if you wait for deficiency or toxicity symptoms to develop, you have already compromised the health of the crop and you r profits. Knowing all factors involved is the first step to managing the substrate pH.
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Whether from a local store, regional supplier, or another farmer down the road, understanding where your soil amendments come from and how they were handled prior to reaching your farm or garden is necessary to ensure you are sourcing the highest quality product with the lowest amount of risk.
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This publication highlights the role of selenium in animal nutrition; selenium concentration and distribution in soils and feedstuffs (grains and forages) produced in various parts of the United States and in Georgia; disorders resulting from Selenium deficiency or toxicity; various methods of selenium supplementation; and recommendations for selenium management in Georgia. This publication is intended to serve as an educational resource for university researchers and Extension specialists, county Extension agents and livestock, forage and feed producers, among others.
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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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C 1077
Cover Crop Biomass Sampling
Cover crops are one of the most important practices that farmers can use to improve their soils and the sustainability of their production system. Knowing how much biomass there is in a field is a critical piece of information for cover crop management. Part 1 of this circular provides a step-by-step guide to taking a sample that will be representative of your field. Part 2 provides additional steps for preparing a fresh cover crop sample to send to the Agricultural and Environmental Services Laboratory so it can be analyzed to determine nitrogen availability to the following crop. Equation examples and data sheets are also provided in order to help users calculate necessary information for submission using the given formulas.
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The University of Georgia Agricultural and Environmental Services Laboratories offer soil salinity testing to help farmers and the general public diagnose and manage problems associated with soil salinity. By definition, a saline soil contains excess soluble salts that reduce the growth of most crops or ornamental plants. This publication discusses soil salinity testing, data interpretation and recommendations, specifically those pertaining to the University of Georgia.
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Cation exchange capacity (CEC) is a measure of the total negative charges within the soil that adsorb plant nutrient cations such as calcium (Ca2+), magnesium (Mg2+) and potassium (K+). As such, the CEC is a property of a soil that describes its capacity to supply nutrient cations to the soil solution for plant uptake.
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This publication primarily focuses on rear discharge, twin spinner spreaders common for poultry litter application in the southeast.
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