 | Soils, Crops and Fertilizer Use |
 |  | About this manual |
| | Acknowledgements |
|  | Chapter 1: Down to earth - Some Important Soil Basics |
| | What is soil, anyway? |
| | Why do soils vary so much? |
| | Topsoil vs. subsoil |
| | The mineral side of soil: sand, silt, and clay |
| | Distinguishing "tropical" soils from "temperate" soils |
| | Organic matter - a soil's best friend |
| | The role of soil microorganisms |
| | Chapter 2: Trouble-shooting soil physical problems |
| | Getting to know the soils in your area |
| | Soil color |
| | Soil texture |
| | Soil tilth |
| | Soil water-holding capacity |
| | Soil drainage |
| | Soil depth |
| | Soil slope |
| | Chapter 3: Basic soil conservation practices |
| | Rainfall erosion |
| | Wind erosion |
| | Chapter 4: Seedbed preparation |
| | The what and why of tillage |
| | Common tillage equipment |
| | The abuses of tillage and how to avoid them |
| | Making the right seedbed for the crop, soil, and climate |
| | How deep should land be tilled? |
| | How fine a seedbed? |
| | Some handy seedbed skills for intensive vegetable production |
| | Chapter 5: Watering vegetables: When? How Often? How Much? |
| | It pays to use water wisely |
| | Some common watering mistakes and their effects |
| | Factors influencing plant water needs |
| | Ok, so get to the point! how much water do plants need and how often? |
| | Some methods for improving water use efficiency |
| | Chapter 6: Soil fertility and plant nutrition simplified |
| | Let's Make a Deal |
| | How plants grow |
| | Available vs. unavailable forms of mineral nutrients |
| | Soil negative charge and nutrient holding ability |
| | Soil pH and how it affects crops growth |
| | Important facts on the plant nutrients |
| | Chapter 7: Evaluating a soil's fertility |
| | Soil testing |
| | Plant tissue testing |
| | Fertilizer trials |
| | Using visual "hunger signs" |
| | Chapter 8: Using organic fertilizers and soil conditioners |
| | What are organic fertilizers? |
| | Organic vs. chemical fertilizers: which are best? |
| | Some examples of successful farming using organic fertilizers |
| | How to use organic fertilizers and soil conditioners |
| | Chapter 9: Using chemical fertilizers |
| | What are chemical fertilizers? |
| | Are chemical fertilizers appropriate for limited-resource farmers? |
| | An introduction to chemical fertilizers |
| | Common chemical fertilizers and their characteristics |
| | The effect of fertilizers on soil pH |
| | Fertilizer salt index and "burn" potential |
| | Basic application principles for N, P, and K |
| | Fertilizer application methods explained and compared |
| | Troubleshooting faulty fertilizer practices |
| | Getting the most out of fertilizer use: crop management as an integrated system |
| | Understanding fertilizer math |
| | Chapter 10: Fertilizer guidelines for specific crops |
| | Cereals |
| | Pulses (grain legumes) |
| | Root crops |
| | Vegetables |
| | Tropical fruit crops |
| | Tropical pastures |
| | Chapter 11: Liming soils |
| | The purpose of liming |
| | When is liming needed? |
| | How to measure soil pH |
| | How to calculate the actual amount of lime needed |
| | How and when to lime |
| | Don't overlime! |
| | Chapter 12: Salinity and alkalinity problems |
| | How salinity and alkalinity harm crop growth |
| | Lab diagnosis of salinity and alkalinity |
| | Appendixes |
| | Appendix A: Useful measurements and conversions |
| | Appendix B: How to determine soil moisture content |
| | Appendix C: Spacing guide for contour ditches and other erosion barriers* |
| | Appendix D: Composition of common chemical fertilizers |
| | Appendix E: Hunger signs in common crops |
| | Appendix F: Legumes for green manuring and cover-cropping in tropical and subtropical regions |
| | Appendix G: Some sources of technical support |
| | Appendix H: A bibliography of useful references |
Getting to know the soils in your area
As explained in Chapter 1, it's difficult to make any useful generalizations about the soils of the tropics and subtropics. Soil-forming factors like climate, parent rock, time, topography, vegetation, and management interact in countless patterns. It's not unusual to find two or more soils on one small farm that vary markedly in texture, depth, slope, and other important features.
Here are the best ways of getting to know your area's soil's:
• Visit with farmers and walk through their fields with them. They're the ones most intimately involved with the land and can provide a wealth of useful information on local soils, their behavior, and productivity.
• Arrange for a soils field tour of your area with an agronomist or extension agent.
• Consult soil survey reports or other soil studies on your area. Soil specialists have devised several taxonomy systems to classify soils, first into orders and groups made up of hundreds of soils, progressing down to a very specific series consisting of several closely related soils that share many similar Profile features. (A soil profile is a vertical slice of soil that includes the topsoil, subsoil, and some of the parent material below.) Of the several taxonomy systems, the one developed in the 1970's by the the USDA in cooperation with other countries has become the most widely used. The terms oxisol and ultisol used in Chapter 1 refer to two soil orders in in this system that comprise hundreds of soils formed under tropical and subtropical conditions. (However, not all warm climate soils belong to these two groups, as explained in Chapter 1.)
NOTE: When reading a soil survey report, don't be intimidated by the technicalities and fancy terms. What's most important to farmers and extension workers is how a soil behaves when farmed - not what order or series it belongs to.
HOW TO EVALUATE A SOIL AND DIAGNOSE PHYSICAL PROBLEMS
Using a shovel and a homemade device to measure slope, it's fairly easy to evaluate the 6 major physical characteristics that determine a soil's behavior and management needs:
• TEXTURE
• DRAINAGE
• TILTH
• DEPTH
• WATER-HOLDING CAPACITY
• SLOPE
Let's cover them one at a time. But wait a minute, we haven't said anything about SOIL COLOR - where does it fit in?
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