Soil Management Guide REVISED 2008 This document can be cited as follows: Manitoba Agriculture, Food and Rural Initiatives, 2008. Soil Management Guide. Table of Contents 1. Understanding the Soil Landscapes of Manitoba 5 Introduction 5 What is soil? 5 Why are soils important? 6 Soil variation 7 Why are there so many different soils found throughout Manitoba? 7 How were soils formed? 8 What are the basic soil properties? 11 Texture 11 Structure 13 Colour 14 Bulk Density 14 Drainage 15 Calcium Carbonate Content 16 How do we organize and classify soils? 17 2. Using Soil Survey Information 25 What is soil survey? 25 What are soil survey reports? 26 Map Information 26 Why is map scale important? 27 Why are detailed soil survey reports required for in-fi eld assessments? 30 Options for data collection when detailed soil survey information is unavailable 30 Interpretive maps 31 Agriculture capability for Manitoba 31 How does agriculture capability compare to the crop insurance Soil Productivity Index ratings? 33 Irrigation suitability 34 Soil suitability for irrigated potato production 34 Other assessment ratings 34 Provincial soil concept 40 Newdale Series (NDL) 41 3. Water Use and Moisture Management 42 Soil moisture defi nitions for plant growth 42 Soil moisture defi nitions for other purposes 45 Reporting soil moisture 45 SOIL MANAGEMENT GUIDE 1 Water movement through soil 46 Basic water movement principles and rules of thumb 47 How far will an inch (25 millimetres) of water move into a soil profi le? 47 Water management strategies 50 4. Nutrient Management 52 Why is nutrient management necessary? 52 Leaching of nitrate-nitrogen to groundwater 52 Phosphorus runoff into surface waters 53 Stream and drain order criteria 55 Regulation of Manure Nutrient Management in Manitoba 56 Basics of nutrient management 59 Challenges to nutrient management 61 Riparian management 61 5. Soil Salinity 63 Background 63 Conditions required for soil salinity 65 Crop response to salinity 67 Consult soils report 69 Site visit 69 Field symptoms 69 Measuring salinity in the fi eld 70 Measuring salinity in the laboratory 72 Recommendations 73 Primary salinity 73 Secondary salinity 73 Follow-up monitoring 75 6. Drainage Management 76 Background 76 A. Surface Drainage 77 B. Tile Drainage 77 Consult soils report 80 Site visit 81 Laboratory analysis 82 Recommendations 82 A. Surface drainage 82 B. Tile drainage 82 Follow-up monitoring of drained fi elds 83 2 SOIL MANAGEMENT GUIDE 7. Soil Erosion 84 A. Wind erosion 84 Background 84 Quick facts 84 Consult soils report to assess risk of wind erosion 85 Conduct site visit to assess risk/evidence of wind erosion 85 Recommendations 87 B. Water Erosion 88 Background 88 Quick facts 89 Consult soils report to assess risk of water erosion 89 Conduct site visit to assess risk/evidence of water erosion 90 Recommendations 90 C. Tillage Erosion 91 Background 91 Quick facts 92 Consult soils report to identify areas prone to tillage erosion 94 Site visit to identify areas prone to tillage erosion 95 Recommendations to reduce tillage erosion 95 Follow-up monitoring 97 8. Tillage, Organic Matter and Crop Residue Management 98 A. Tillage 98 Defi ning Tillage Systems 98 B. Organic Matter Depletion 100 Consult soils report 101 Site Assessment 102 Recommendations 102 Follow-up monitoring 102 C. Crop Residue Management 103 Spring 103 Summer 104 Fall 105 Snow Trapping Potential (STP) 105 If You Must Burn 106 Winter 107 Spring (Year 2) 108 9. Soil Compaction 109 Background 109 Consult the soils report to assess compaction 111 Conduct a site visit to assess compaction 111 Recommendations to prevent and correct soil compaction 112 Follow-up monitoring 113 SOIL MANAGEMENT GUIDE 3 10. Soils Information for Planning Purposes 114 Introduction 114 A. Land Use Planning 115 B. Section A of the Environmental Farm Plan 116 Recommendations 117 C. integrated Watershed Management Planning 119 11. Greenhouses Gases in Agriculture 121 What is climate change? 121 What are the agricultural contributions to climate change? 122 What are “Carbon Sinks”? 124 Land management to reduce greenhouse gas emissions 124 Soil management to reduce greenhouse gas emissions 125 Nutrient management to reduce greenhouse gas emissions 126 Composting manure to reduce greenhouse gas emissions 127 12. Other Applications of Soils Information 129 13. Summary 130 14. References 131 15. Glossary 137 16. Appendices 143 A. Detailed Soil Survey Protocol (1:20 000 scale) 143 B. How to Use a Soil Survey Report 144 C. Other Sources of Land Information 146 D. Sources of dilute hydrochloric acid 147 E. Drinking water quality guidelines for humans, livestock 147 F. Determining Soil Texture By Feel 148 G. Generalized Surface Texture of Soils in Southern Manitoba 149 H. pH Status of Manitoba Soils 150 I. Organic Carbon Status of Manitoba Soils 151 J. Calcium Carbonate Content of Manitoba Soils 152 K. Unit Conversion Table 153 4 SOIL MANAGEMENT GUIDE 1 Understanding the Soil Landscapes of Manitoba Introduction Soil management, or soil conservation, deals with some aspect of protecting soil resources and using soils in a sustainable manner. Effective soil conservation in agriculture hinges on fi ve basic principles: 1. Keeping soil in place by reducing tillage practices 2. Maintaining or improving soil quality parameters, such as organic matter, bulk density, earthworms, desirable soil structure, etc. 3. Managing and protecting water supplies 4. Planning a crop rotation system made up of crops that are profi table and protect soil quality 5. Applying only the amount of inputs needed to achieve reasonable crop production targets This publication focuses on the fi rst three principles. Additional information on items #4 and #5 are found in the Soil Fertility Guide, Field Crop Production Guide and Guide to Crop Protection published by Manitoba Agriculture, Food and Rural Initiatives and in other agronomy-related publications. To fully appreciate and understand the principles of soil management, one must understand the soil itself. The fi rst part of the guide deals with how soils are formed and classifi ed. The latter section uses these principles to identify certain soils (under certain conditions) that would benefi t the most from a particular soil conservation practice. What is soil? Soils comprise the uppermost layer of the earth’s surface. They were developed by the action of climate on rock and sediments under the infl uence of organic life. The fi rst interest in the soil was related to its ability to produce plants for food and fi bre. In this context, soil is defi ned as the collection of natural bodies on the earth’s surface supporting or capable of supporting plants (Brady, 1984). CHAPTER 1 – UNDERSTANDING THE SOIL LANDSCAPES OF MANITOBA 5 Why are soils important? Soils are required for food production and for fi ltration of water. However, only 1/16 of the earth’s surface has soil that is suitable for growing crops. Of the 160 million acres (65 million hectares) in Manitoba, only 19 million acres (7.7 million hectares) have potential for agriculture. Much of this land has been settled over time, and is either being lost to urbanization or being mismanaged so that erosion, salinity, compaction and organic matter losses have made the soil less productive. Over a 10 year period from 1991 to 2001, approximately 36,600 acres (14,640 hectares) of land in Manitoba has been subdivided into building lots for non-agricultural land uses (Land Use Planning Group, 2003). Table 1.1. Relative area of various segments of Manitoba Million Acres Million Hectares (approx.) (approx.) Total Area – Manitoba 160 65 Total Land Surface - Manitoba 136 55 Total Land Area – Agro-Manitoba 26 10.5 Land in Farms – Agro-Manitoba 19 7.7 Improved Land (Crops, Fallow, Pasture) 13 5.3 Unimproved Pasture 4 1.6 Other (e.g. yard sites, etc.) 2 0.8 (Source: Manitoba Agriculture Yearbook 2003). Table 1.2. Land use data within agro-Manitoba as based on satellite imagery from 1999-2002 (Manitoba Conservation – Manitoba Remote Sensing Centre, 2002). Land use Total Total (ac) (ha) Agricultural Cropland 12,161,607 4,921,648 Trees 6,279,339 2,541,167 Water Bodies 620,708 251,193 Grassland/Rangeland 6,001,550 2,428,751 Wetlands 2,222,681 899,491 Forages 1,038,032 420,078 Urban & Transportation 828,344 335,220 Total 29,152,261 11,797,548 6 SOIL MANAGEMENT GUIDE “ In the past, many industrial developments were put on poor soils because the land was (inexpensive), but in the future information on soils and the environment must be consid- ered much more carefully to avoid repeating past mistakes. Many of our (waste disposal) problems can be solved and mistakes avoided by increased use of soil maps together with other environmental information.” (Olson, 1984). The fi rst step in sustainable soil management is ensuring that the soil will support the land use activity. For example, only the better agricultural soils in Manitoba will support grain and vegetable production, while more marginal agricultural soils will support forage and pasture-based production. For this reason, agricultural develop- ment should only occur in areas where the soil resource will support the agricultural activity. The only way to do this is to understand the soil resource that is available. Soil variation Soils vary signifi cantly in their properties. They may be deep in some places, shallow in others, black or gray in colour, sandy or clayey in texture. Although the soil mantle covering Manitoba is far from uniform, all soils have some common factors. For example, all soil is a mixture of organic and mineral material plus water and air. While the major components remain the same, the proportion of each component in this mixture varies from soil to soil.