soil fertility and fertilizers an introduction...

i

SOIL FERTILITY AND FERTILIZERSAn Introduction to Nutrient Management

SEVENTH EDITION

JOHN L. HAVLINJAMES D. BEATONSAMUEL L. TISDALEWERNER L. NELSON

Full file at http://testbank360.eu/solution-manual-soil-fertility-and-fertilizers-7th-edition-havlin

Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458.Pearson Prentice Hall. All rights reserved. Printed in the United States of America. This publication is protected byCopyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in aretrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, orlikewise. For information regarding permission(s), write to: Rights and Permissions Department.

Pearson Prentice Hall™ is a trademark of Pearson Education, Inc.Pearson® is a registered trademark of Pearson plcPrentice Hall® is a registered trademark of Pearson Education, Inc.

Pearson Education LTD.Pearson Education Singapore, Pte. LtdPearson Education, Canada, LtdPearson Education–JapanPearson Education Australia PTY, LimitedPearson Education North Asia LtdPearson Educaçion de Mexico, S.A. de C.V.Pearson Education Malaysia, Pte. Ltd

10 9 8 7 6 5 4 3 2 1ISBN 0-13-861899-2


iii

CONTENTS

Chapter 1: Introduction 1

Chapter 2: Basic Soil-Plant Relationships 2

Chapter 3: Soil Acidity and Alkalinity 5

Chapter 4: Nitrogen 8

Chapter 5: Phosphorus 11

Chapter 6: Potassium 14

Chapter 7: Sulfur, Calcium, and Magnesium 16

Chapter 8: Micronutrients 20

Chapter 9: Soil Fertility Evaluation 25

Chapter 10: Basics of Nutrient Management 32

Chapter 11: Nutrients, Water Use, and Other Interactions 35

Chapter 12: Economics of Plant-Nutrient Use 37

Chapter 13: Agricultural Productivity and Environmental Quality 39


iv

INTRODUCTION

One of the greatest challenges of this and future generations will be to develop andimplement soil, crop, and nutrient management technologies that enhance plantproductivity and the quality of our soil, water, and air. If we do not improve and/orsustain the productive capacity of our fragile soils, we will be unable to meet the foodand fiber demand of our growing population. To meet this challenge, educators mustengage students to develop qualitative and quantitative skills necessary to understand andmanipulate chemical, biological, and physical properties and interrelationships in the soil,plant, atmosphere continuum that influence and control nutrient availability.

The purpose of the Instructors Manual is to provide educators with 1) learning objectivesfor each chapter in the textbook, 2) summaries of basic information and principlescovered in each chapter, 3) questions that educators can use to assess student learning,and 4) worked examples of selected quantitative questions. The situations and data usedin each worked problem can be changed to represent your specific region or soil and cropmanagement systems. The intent is to illustrate essential quantitative skills. Instructorsmay contact John L. Havlin ([email protected]; 919-513-4411) to receive anelectronic copy of the Instructors Manual to facilitate development of problem sets andexams.

Comprehensive Learning Goals

The goal of this course is for students to attain a comprehensive understanding of plantnutrition, soil fertility, and nutrient management so that he or she can (1) describe theinfluence of soil chemical, biological, and physical properties and processes on nutrientavailability to plants; (2) identify plant nutrition and soil fertility problems andrecommend proper corrective action; and (3) identify soil and nutrient managementpractices that maximize crop productivity and profitability while maintaining orenhancing soil productivity and environmental quality. Within each of these generalgoals, learning objectives will be outlined for each chapter to adhere to these courseobjectives:

1. Describe how plants adsorb nutrients and how the soil system supplies essentialnutrients.

2. Identify and describe plant nutrient deficiency symptoms and methods used toquantify nutrient problems.

3. Describe how soil organic matter, cation exchange capacity, pH, parent material,climate, and human activities affect nutrient availability.

4. Evaluate nutrient and soil amendment materials on the basis of content, use, andeffects on the soil and the crop.

5. Quantify, using basic chemical principles, application rates of nutrients andamendments needed to correct plant nutrition problems.

6. Describe nutrient response patterns, nutrient efficiency, and the economics of nutrientuse.

7. Describe and evaluate soil and nutrient management practices that either impair orsustain soil productivity and environmental quality.


1

CHAPTER 1Introduction

LEARNING OBJECTIVES 1. Describe world food security in terms of projected population growth and current and

potential capacity to produce food and fiber.2. Assess the role and impact of agricultural technologies on current and potential productive

capacity of agricultural lands and their importance on food security.3. Identify factors affecting crop productivity and distinguish between controllable and

uncontrollable factors. Utilize Leibig’s Law of the Minimum to solve problems in cropproduction systems.

4. Identify the criteria used for establishing essentiality of an element in plant nutrition andquantify the relative concentrations of essential macro and micronutrients in plants.

5. Describe the relationship between increasing or decreasing plant nutrient concentration onplant yield with respect to both nutrient deficiency and toxicity.

SUMMARY1. Although approximately 1 billion people throughout the world are currently at risk of hunger,

famine and hunger are expected to decrease by 2050.2. Development of agricultural technology has resulted in substantial increases in food

production since 1950, while the number of farms and farmers has decreased resulting in anequivalent increase in the number of acres per farm.

3. In the U.S., the increase in crop yields over the last 50 years in predominately due toadvances in plant genetics, nutrient and pest management, and other soil and cropmanagement practices.

4. Factors that limit crop yield potential are classified into climatic, soil, and crop factors.Environmental factors were considered in relation to their effect on plant growth, as well astheir impact on limiting the crop response to applied plant nutrients.

5. Established in 1862, Leibig’s Law of the Minimum is an important principle in cropproduction and simply means that crop yield can not be increased until the most limitingcontrollable factor is eliminated or reduced. Further yield increases can only occur when thenext most limiting factor is reduced or eliminated and so on (Fig. 1.7).

6. Figure 1.9 shows that as nutrient concentration in tissue increases yield increases until thenutrient no longer limits yield (sufficient range). Yield can be decreased at excessively highor toxic nutrient levels.

7. All elements absorbed by plants are not necessarily essential to plant growth. The termfunctional or metabolic nutrient includes any element that functions in plant nutrition,regardless of whether its action is specific. It was suggested that this term might avoid theconfusion that sometimes occurs in a definition of essential plant nutrients.

8. Twenty elements have been found to be essential to plant growth. Not all are required by allplants, but all are necessary to some plants. Nutrients required by plants are C, H, O, N, P, K,Ca, Mg, S, B, Fe, Mn, Cu, Zn, Mo, Cl, and Ni. In addition, some plants also need Co, V, Na,and Si. Elements other than C, H, and O are termed mineral nutrients. The elements N, P, K,Ca, Mg, and S are macronutrients where the latter elements are micronutrients.

QUESTIONS1. Assess the risk of famine in the world over the next fifty years. What will the world

population be in 2050?


2

2. Crop yields have increased more in the last fifty years than in the two hundred years before1950. What factors are related to the increased yields since 1950?

3. Using Tables 1-2 and 1-3, plot the total food production and total number of people at risk ofhunger projected over the next sixty years. What can you conclude?

4. Using Figure 1-5, identify which land uses have increased at the expense of forests andrangelands.

5. In Table 1-7, prioritize the climate, soil, and crop factors limiting crop yield potential frommost to least effect on reducing yield. Which of these factors can be managed?

6. Define the Law of the Minimum and provide an example.7. List the essential nutrients required in plants.8. Crop yields have been increasing with time because of advances in tillage, varieties, pest

control, fertilization, and so on. What factor(s) will ultimately limit further yield increases?9. List three factors that would cause the difference between the response curves in Figure 1-11.10. Among the environmental factors limiting crop response to nutrients, which is probably the

most easily and inexpensively changed?

CHAPTER 2Basic Soil–Plant Relationships

LEARNING OBJECTIVES1. Describe and quantify cation and anion exchange in soils. The influence of specific minerals

and other soil components on exchange capacity and exchange reactions should be identifiedand related to permanent and pH dependent charge.

2. Quantify the relationship between atomic and equivalent weight of ions and compounds. Usethese relationships to calculate CEC, base saturation, and other ion exchange reactions insoil. Use the relationship between soil pH and base saturation to quantify soil amendments.

3. Discuss the influence of buffer capacity on nutrient retention and availability; and chemicaland physical properties and soil management practices that affect buffer capacity.

4. Describe the importance of root interception, mass flow, and diffusion on supplying cationsand anions to plant roots. Estimate the quantity of root interception and mass flow toaccurately assess the importance of diffusion on nutrient availability. Discuss the influence ofsoil physical properties, buffer capacity, and environment on diffusion.

5. Discuss the influence of passive and active processes on nutrient adsorption by plant rootsand transport in plants

SUMMARY1. The concentration of nutrients in the soil solution and ultimately nutrient availability is

controlled by many inorganic, organic, and microbial reactions in the soil.2. Ion exchange on the surface of clay minerals, inorganic compounds, and OM is one of the

most important chemical properties influencing nutrient availability. The (+) and (-) surfacecharges originate in the development of the layer silicate clay minerals and on broken edges.

3. Clay minerals are classified into 1:1 and 2:1minerals representing the ratio of Si tetrahedraland Al octahedral layers within the mineral structure. 2:1:1 minerals include a hydroxidelayer between 2:1 layers (Fig. 2.4 and 2.5).

4. Isomorphic substitution of Al for Si in the Si tetrahedra and Mg for Al in the Al octahedrallayer produces the majority of negative or permanent charge in clay minerals. Increasingisomorphic substitution increases the negative charge or cation exchange capacitiy (CEC).


3

5. pH dependent charge is located on the broken edges of clay minerals and on organic matter.As pH increases, negative surface charge (CEC) increases, while positive surface charge(anion exchange capacity, AEC) decreases.

6. The quantity of CEC or AEC is expressed as meq/100g soil.7. Lyotropic series represents the strength of adsorption of cations on the mineral surface and is

represented by Al3+ > H+ > Ca2+ > Mg2+ > K+ = NH4+ > Na+ (decreasing strength of

adsorption).8. Base saturation % represents the proportion of the CEC occupied by basic cations.9. Buffer capacity (BC) represents the ability of the soil to maintain or replenish nutrient

concentration in the soil solution. BC increases with increasing CEC, OM, and clay content.10. Soil solution ions are transported to the root surface by mass flow and diffusion, while roots

also intercept adsorbed nutrients. Mass flow represents transport in solution as roots take upwater, while diffusion is transport through a concentration gradient (high to lowconcentration). Diffusion is described by Fick’s Law. Diffusion increases with increasingsolution concentration, increasing soil water content, decreasing buffer capacity, anddecreasing diffusion path.

11. Nutrient absorption by roots and cells is governed by passive and active ion uptake. Passiveuptake represents transport by diffusion and ion exchange, while active uptake is transportagainst a concentration gradient and requires energy provided by carbohydrate respiration.Transporter mechanisms are involved in both passive and active uptake across impermeablemembranes, which are specific for specific nutrients.

QUESTIONS1. Define cation exchange capacity (CEC). What units are commonly used to express CEC?2. What is the origin of CEC in mineral soil colloids and identify factors that influence CEC.3. Explain the influence of the following on CEC in soils.

a. increasing pH from 6.0 to 7.5b. increasing weathering intensity (over the long term)c. adding bases such as Ca+2 or Mg+2

4. Which clay minerals would likely be present in a weathered acid soil?5. Why are 2:1 clay minerals more common in soils of the Midwest or Great Plains regions of

North America?6. As soils age from thousands of years of weathering, some soil properties change. List two of

these properties and how these changes might effect soil productivity.7. What are the two sources of negative charge in clay minerals?8. What is meant by buffer capacity (BC) and what soil properties determine the soil BC?9. 30 lb P/a is added to two soils. The resulting solution P concentration in soil A is 4 times lower

than soil B, although plant uptake in soil A is greater than soil B. What is causing thedifferences in these soil and plant P observations?

10. What is the lyotropic series for cations and anions and does this explain nutrient mobility insoils and availability to plants? What is the basis for the lyotropic series for cations?

11. In addition to clay minerals, what other soil constituents contribute to total CEC?12. How does CEC buffer nutrient concentration in soil solution?13. Why does anion adsorption appear to be of little importance in most agricultural soils? Why

are AECs of ultisols usually greater than those of mollisols?14. With what type of soil would the ammonium acetate method provide a good estimate of

CEC? On what types would it provide a poor estimate? Explain why.15. What is active and passive absorption of elements by root cells? How are the inner and outer

space of cells involved? What is the proposed mechanism that describes active absorption?


4

16. You are addressing a group of farmers and business managers who understand cropproduction but are not familiar with the technical aspects of plant nutrition and soil fertility.You have to explain the nature of cation exchange and why it is important to cropproduction. How would you proceed? After the speech, someone asks why Cl- and NO3

- willleach from soils but H2PO4

-, which also has a negative charge, will not. What is your answer?17. What is root interception?18. Mass flow can potentially move enough Ca and Mg to the plant root to meet the nutritional

needs. Which anions would most likely move with them and why?19. Describe the relative importance of root interception, diffusion, and mass flow in nutrient

transport to plant roots? What is the effect of soil texture on these three mechanisms? Why?20. What soil factors influence diffusion of nutrient ions to roots? Describe and explain a

practical way of improving the diffusion of nutrients?21. Briefly describe the influence of the following on ion diffusion in soils.

a. temperatureb. soil moisturec. soil textured. buffer capacitye. specific ion (i.e one ion vs another)

22. A solution contains 20 ppm Ca+2. Express the Ca+2 concentration in the following termsa. grams Ca+2 in 1,000,000 ml water (ml = milliliter = 0.001 liter)b. grams Ca+2 in 100 ml waterc. % Ca+2 in the 100 ml waterd. mg Ca+2/kg water [mg = milligram = 0.001 gram = 0.000001 kilogram (kg)]e. Molarity (M or moles Ca+2/liter)

23. A solution contains 0.1 M KOH. Calculate the K+ concentration in the following termsa. g K+/ lb. mg K+/ mlc. mg K+/ kgd. ppm K+

e. % K+

24. A soil contains 1000 ppm Ca+2 (surface 6 inches). Express the Ca+2 concentration in the following terms.

a. grams Ca+2/1,000,000 g soilb. grams Ca+2/100 g soilc. % Ca+2

d. mg Ca+2/kg soile. lbs Ca+2/afs (afs= acre furrow slice or 1 acre area-6 inches deep)

25. A soil was sampled to a depth of 6 inches. The sample was analyzed for several cations withthe following results: Ca+2 = 453 ppm; Mg+2 = 82 ppm; K+ = 227 ppm; Na+ = 28 ppma. Calculate the lbs/afs for each nutrient.b. Calculate the % content for each nutrient.c. Calculate the mg/kg for each nutrient.

26. A solution contains the following: Ca+2 = 1000 ppm; Mg+2 = 480 ppm; K+ = 400 ppm; Na+ =460 ppma. Calculate the M (mole/liter) for each nutrient.b. Calculate the % concentration for each nutrient.c. Calculate the mg/kg for each nutrient.

27. There are 6 x 1023 ions of Ca+2 in 1 mole.a. How much does this many Ca+2 ions weigh?


soil fertility and fertilizers an introduction...

Documents