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UNIVERSITI PUTRA MALAYSIA

NITROGEN CONTRIBUTION BY GROUNDNUT (ARACHIS HYPOGAEA L.) IN A ROTATIONAL CROPPING SYSTEM ON AN

ULTISOL

ANUAR BIN ABDUL RAHIM

FH 1991 2

NITROGEN CONTRIBUTION BY GROUNDNUT (Arachis hypogaea L.) IN A ROTATIONAL CROPPING SYSTEM ON AN ULTISOL

By


Thesis Submitted in Fulfilment of the Requirement for the Degree of Doctor of Philosophy in the Faculty

of Agriculture, Universiti Pertanian Malaysia

April 1991

ACKNOWLEDGEMENTS

My sincere appreciation is extended to Professor Othman Yaacob and

Associate Professor Zulkifli H. Shamsuddin for their valuable guidance provided

during the planning and execution of this study as well as in the preparation of

this manuscript.

Special appreciation is also extended to Professor G. H. Elkan for his

assistance during my study-leave to pursue the courses at North Carolina State

University. I would like to thank Mr. T. J. Schneeweis for the computer time

spent in the statistical analyses.

Gratitude is expressed to my family and colleagues for their

encouragement and support throughout my educational career.

I am deeply indebted to the Public Services Department of Malaysia for

awarding me a scholarship during my study-leave both at Universiti Pertanian

Malaysia and North Carolina State University.

11

TABLE OF CONTENTS

ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , viii

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

ABSTRAK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , XlV

CHAPTER

ONE: INTRODUCTION .................................... 1

1WO: REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Ultisols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Soil Factors Limiting Plant Growth . . . . . . . . . . . . . . . . . . . . . . . 7

Nitrogen Contribution by Legumes in a Crop Rotation System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Symbiotic N2 Fixation by Legumes . . . . . . . . . . . . . . . . . . . . . . 16

Transfer of Symbiotically Fixed N to Non-legumes . . . . . . . . . . . 18

Effect of Soil Acidity on Symbiotic Growth of Legumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

THREE: MAXIMIZATION OF N2 FIXING CAPACITY OF GROUNDNUT ON AN ULTISOL BY ALLEVIATING SOIL ACIDITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Experiment 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Experiment 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 50


FOUR: NITROGEN CONTRIBUTION BY GROUNDNUT FOR GROWTH OF MAIZE IN A ROTATIONAL CROPPING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67


FIVE: ALLEVIATION OF ADVERSE EFFECTS OF SOIL ACIDITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Experiment 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 102

SIX: SUMMARY AND CONCLUSION . . . . . . . . . . . . . . . . . . . . . . 108

BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 1

APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

VITA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1

LIST OF TABLES

Table

1 Example of N2 Fixation Rates by Some Tropical ugumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2 Physico-chemical Characteristics of Bungor sandy clay loam (Typic Paleudult) in the Preliminary Liming Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 32

3 Effect of Lime on Yield of Uninoculated Groundnut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4 Effect of Lime on N Concentration and N Accumulation in Groundnut . . . . . . . . . . . . . . . . . . . . . . . 39

5 Effect of Lime on Yield of Maize . . . . . . . . . . . . . . . . . . . . . . . . 43

6 Effect of Inoculation on Top Dry Matter Yield of Groundnut, at D30' Grown on (a) Unlimed and (b) Limed Bungor sandy clay loam . . . . . . . . . . . . . . . . . . . . 5 1

7 AI Saturation, Ca Concentration and pH of Unlimed and Limed Bungor sandy clay loam in the Inoculation Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

8 Effect of Inoculation on Nodule Number (NN-per plant) and Leaf N Concentration (g kg-1) of Groundnut at D30' Grown on (a) Unlimed and (b) Limed Bungor sandy clay loam . . . . . . . . . . . . . . . . . . . . . . . . 53

9 Comparison between Effects of Bradyrhizobium strain CB756 on Dry Matter Yield and N Accumulation in Groundnut cv. V13, at D106, Planted in Glasshouse and in the Field (Experiment 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

10 Effect of Lime and Inoculation with Bradyrhizobium strain CB756 on Haulm Dry Matter, Nodule Number, Leaf N and Ca Concentration of Groundnut cv. V13 at D30

. . . . . . . . . . . . . . . . 58

v

1 1 Effect of Lime on Nodule Number, Leaf N Concentration, Top Dry Matter after 30 Days and Pod Yield (D30) of Groundnut cv. Mat jam Inoculated with Bradyrhizobium strain NC92 Grown on Bungor sandy clay loam . . . . . . . . . . . . . . . . . . . . . . . 62

12 Groundnut-Maize Sequence Used in the Rotational Cropping System on an Ultisol ( 1981-1984) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

13 Dry Matter Yield of Groundnut in the Rotational Cropping System (1981-1984) . . . . . . . . . . . . . . . . . . . 75

14 Plant N Content of Groundnut in the Rotational Cropping System (1981-1984) . . . . . . . . . . . . . . . . . . . 77

15 Available N in Soil before Sowing in Each Season in the Rotational Cropping System ( 1981-1984) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

16 Dry Matter Yield of Maize under Different Legume Intensity in the Rotational Cropping System (1981-1984) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

17 Effect of Fertilizer N on Maize Grain Yield during (a) First ( 1981-1982) and (b) Second (1983-1984) Crop Cycles in the Monoculture Cropping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

18 Regression Analysis of Grain Yield of Maize during (a)lst (1981-1982) and (b)2nd (1983-1984) Crop Cycles in Monoculture Cropping System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

19 Total DM (mt ha-1) and N Accumulation (kg N ha-1) of Maize on an Ultisol Receiving Varying Number of Groundnut Crops or Rates of Fertilizer-N at Puchong, Malaysia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

20 Percentage Increase and Fertilizer N Equivalent of DM Yield of Maize in the Rotational Cropping System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

VI

21 Pod Yield of Groundnut Supplied with Different Rates and Sources of Cations . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

22 Effects of CaC03 and MgC03 on AI Saturation and pH of Bungor sandy clay loam . . . . . . . . . . . . . . . . . . . . . . . 104

23 Effects of Different Rates and Sources of Ca on Nodule Number and Leaf N Concentration . . . . . . . . . . . . . . . . 104

24 Effects of Different Rates and Sources of Cations on Top Dry Matter of Groundnut (D30) . . . . . . . . . . . . 106

25 Effects of CaS04 and K2S04 on AI Saturation and pH of Bungor sandy clay loam . . . . . . . . . . . . . . . . . . . . . . . 106

26 Analysis of Some Selected Chemical Properties of Bungor sandy clay loam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

27 ANOV A - Effect of Lime on Pod N Accumulation in Groundnut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

28 ANOV A - Effect of Lime on Grain Yield of Maize

29 ANOV A - Effect of Lime on Nodule Number of Groundnut cv. Mat jam Inoculated with

125

Bradyrhizobium NC92 after 30 Days . . . . . . . . . . . . . . . . . . . . . 126

30 ANOV A - Effect of Lime on Pod Yield of Groundnut cv. Mat jam Inoculated with Bradyrhizobium NC92 after 106 Days . . . . . . . . . . . . . . . . . . . . . 126

3 1 Stover Yield and N Accumulation Parameters at Various N Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

32 AI Saturation before Planting of Each Season in Monoculture and Rotational Cropping Systems ( 1st crop cycle) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

33 Effects of Ca, Mg and K Cations on Pod Yield of Groundnut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

34 Effects of CaC03 and MgC03 on Leaf Ca Concentration of Groundnut . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Vll

LIST OF FIGURES

Figure

1 Soil Carbon Model Showing the Decomposition of Plant Residues into Different Soil Organic Matter (SOM) Functional Fractions . . . . . . . . . . . . . . . . 14

2 Rainfall Pattern during the Preliminary Liming Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

3 Influence of Lime on (a) Relative Pod Yield of Groundnut, (b) AI Saturation, (c) Soil Ca Concentration, and (d) Soil pH . . . . . . . . . . . . . . . . . . . . . . . . . . 40

4 Influence of Lime on (a) Relative Yield of Maize, (b) AI Saturation, (c) Soil Ca Concentration, and (d) Soil pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

5 Pod and Grain Yields of (a) Groundnut and (b) Maize as Mfected by Changes in AI Saturation Level of an Ultisol at Puchong, Malaysia . . . . . . . . . . . . . . . . . . . 46

6 Response of Groundnut-Bradyrhizobium strain Combinations on Unlimed (shaded) and Limed Bungor sandy clay loam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

7 Effect of Lime on (a) AI Saturation, (b) Ca Concentration, and (c) pH of Bungor sandy clay loam Planted with Groundnut . . . . . . . . . . . . . . . . . . . 63

8 Relationship between Nodule Number and Leaf N Concentration of Groundnut . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

9 Cropping Seasons and Rainfall Pattern during the Field Trial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

10 Influence of Legume Cropping Intensity on Yield of Maize on Lime-amended Ultisol . . . . . . . . . . . . . . . . 84

1 1 Influence of Fertilizer-N on the Grain Yield of Maize during (a) 1st (1981-1982) and (b)2nd (1983-1984) Crop Cycles . . . .. . . . . . . . . . . . . . . . . . . . . . 87

V111

12 Effect of Fertilizer-N on the Total-N Accumulation during (a) 1st (1981-1982) and (b) 2nd Crop Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

13 Effect of Reducing AI Saturation and the Contribution of Legume and Fertilizer-N on Yield of Maize on an Ultisol (1980-1982) . . . . . . . . . . . . . . . . . . . 97

14 Effects of CaC03 and MgC03 on Pod Yield of Groundnut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

IX

Abstract of the thesis submitted to the Senate of Universiti Pertanian Malaysia in fulfilment of the requirement for the Degree of Doctor of Philosophy.

NITROGEN CONTRIBUTION BY GROUNDNUT (Arachis hypogaea L.) IN A ROTATIONAL CROPPING SYSTEM ON AN ULTISOL

By


April, 1991

Supervisor : Professor Othman Yaacob

Co-supervisor : Associate Professor Zulkifli H. Shamsuddin

Faculty : Agriculture

In Malaysia, about 120,000 ha of highly weathered Oxisols and Ultisols

come off either from rubber or oil palm annually under the replanting

programme. Annual crops such as groundnut and maize are often used as cover

crops, which can replace non-food legume cover crops, during the first four years

under the replanting programme. The acidic nature associated with high

aluminum concentration and low native nitrogen status often pose severe

constraints to the growth and productivity of annual food crops on these

Ultisols.

x

An approach which involved the adoption of advanced legume technology

and liming was hypothesized to reduce these two soil-related constraints

affecting annual food crop production on Ultisols. Using this approach the

following aspects were investigated :

i) the amount of lime needed to reduce the high Al saturation level

(82%) in an Ultisol required for satisfactory growth and yield of

uninoculated groundnut and maIze,

ii) the selection of compatible groundnut cultivar-Bradyrhizobium

strain combination on limed-Ultisol for maximum yield and

legume-N return to the soil,

iii) the amount of legume-N contributed by groundnut inoculated with

selected Bradyrhizohium,

iv) the amount of legume-N contributed by groundnut inoculated with

compatible Bradyrhizobium in three groundnut (L)-maize (M)

sequence - LMLM, MLLM and LLLM in rotational crop system

as estimated in the yield of maize,

v) the correction of soil acidity by chemicals other than lime.

To investigate aspect (i), a short-term experiment and for aspect (iv) a

long term experiment (4 years), were carried out in the field. All other

experiments (ii, iii, and v) were carried out under glasshouse conditions.

Liming an Ultisol with 4 mt GML (ground magnesium limestone) ha-1,

reduced Al saturation in the Bungor sandy clay loam (Typic Paleudult) from 82

Xl

to < 20% and increased the yield of groundnut (cv. V13) by 26% and maize (cv.

Sg. Buluh) fertilized with 90 kg ha-1 of fertilizer N by 71 % compared to control

where no lime was applied. Liming also increased the amount of residual or

legume N by 44 kg N ha-1 which could be returned to the soil (i).

The appropriate Bradyrhizobium selected for groundnut V13 on limed

Ultisol was Bradyrhizobium CB756 (ii). This groundnut-Bradyrhizobium strain

combination further increased the yield and N accumulation in the haulm under

unlimed and limed conditions. The amount of legume N which could be

returned to the soil in plant residue was about 77 under unlimed and 105 kg N

ha-1 under limed conditions (iii), an increase of more than double that

estimated from unimproved Bradyrhizobium in the open field situation (i). As

this was under closed system, the estimate was higher (ii).

In the open field system, however, apart from the first crop in the first

year ( 1981), this groundnut-Bradyrhizobium combination returned as legume-N

an average of 5 1 kg ha-1 of fertilizer N equivalent in the LMLM sequence,

during the four year period ( 1981-1984). In the MLLM sequence, the

accumulative legume N returned after two crops of ground nut was 106 kg ha-1

in the first and 102 kg ha-1 in the second crop cycles. During the same period,

three successive groundnut crops prior to maize (LLLM), the accumulative

legume-N accounted 142 kg ha-1 for the first cycle ( 1981-1982) and 165 kg ha-1

of fertilizer N equivalent for the second (1983-1984) crop cycles.

XlI

The recovery of legume-N in maize from the LMLM sequence was 3 1 %,

and from the MLLM sequence, it was 21 % for the first crop cycle and 25% for

the second crop cycle. In plots receiving three successive groundnut crop

(LLLM), the recovery was 31 and 37% for the first and second crop cycles,

respectively. This gave fertilizer N equivalent between 13-16, 22-26 and 44-61

kg N ha-1. Fertilizer N equivalent to 56 kg N ha-1 which was estimated from

N-uptake response curve from the N-fertilized mono cropping experiment,

represent ca. 35% of the maize N requirement ( 159 kg N ha-1) on limed Ultisol

(iv).

Amending Ultisols with Ca, Mg, and K fertilizer materials other than the

liming materials did not alleviate soil acidity or increase pod yield. However,

CaS04 and K2S04 temporarily reduced AI saturation and increased the top dry

weight of groundnut at 30 days after planting (v).

Throughout the field study the soil pH was maintained at pH 5.5 by

liming with GML. This reduced the AI saturation to ca. 15% and increased

both yield and legume-N contribution to maize. The field study showed that

only the three successive groundnut crops in the LLLM sequence managed to

contributed about a third of the N requirements of maize to achieve maximum

grain yield of 6.4 mt ha-1.

X111

Abstrak tesis yang dikemukakan kepada Senat Universiti Pertanian Malaysia sebagai memenuhi keperluan untuk Ijazah Doktor Falsafah.

SUMBANGAN NITROGEN OLEH KACANG TANAH (Arachis hypogaea L.) DI DALAM SISTEM TANAMAN GILIRAN PADA TANAH ULTISOL

Oleh


April, 1991

Penyelia Profesor Othman Yaacob

Penyelia bersama Profesor Madya Zulkilfli H. Shamsuddin

Fakulti Pertanian

Setiap tahun lebih kurang 120,000 ha tanah terluluhawa Oksisol dan

Ultisol di Malaysia yang ditanam sarna ada dengan getah atau kelapa sawit

adalah di bawah rancangan tanaman semula. Tanaman kontan seperti kacang

tanah dan jagung biasanya ditanam sebagai tanaman menggantikan tanaman

penutup bumi yang bias a ditanam di peringkat awal di bawah rancangan

tanaman semula ini. Sifat keasidan berkaitan dengan kandungan AI yang tinggi

dan kandungan N yang rendah biasanya menghadkan tumbesaran dan daya

produktiviti kedua-dua tanaman tersebut di kawasan tanah Ultisol.

XlV

Penggunaan teknologi tanarnan kekacang dan kadar pengapuran adalah

satu cara rnengatasi rnasalah dua faktor tersebut yang rnenghadkan pengeluaran

tanarnan makanan di kawasan tanah Ultisol. Dengan menggunakan kaedah ini,

aspek-aspek berikut telah dikaji:

i) kadar pengapuran yang diperlukan untuk rnenurunkan tahap

ketepuan AI yang tinggi ke paras yang rnenggalakkan tumbesaran

dan hasil kacang tanah dan jagung yang rnernuaskan di kawasan

Ultisol,

ii) kornbinasi kacang tanah-Bradyrhizobium yang berkesan dipilih dari

segi kaitan dan surnbangan N di kawasan tanah Ultisol yang

dikapur,

iii) surnbangan N daripada kornbinasi kacang tanah-Bradyrhizobium

yang terpilih,

iv) surnbangan N daripada kacang tanah untuk tanarnan jagung

dalarn tiga sis tern tanarn bergiliran kacang tanah (L) - jagung

(M) : LMLM, MLLM dan LLLM yang dianggarkan rnelalui hasil

tanarnan jagung berbaja N,

v) rnengatasi keasidan tanah dengan bahan kimia selain daripada

kapur.

Untuk rnengkaji aspek (i), kajian jangkarnasa pendek dan untuk (iv),

kajian jangkarnasa panjang (4 tahun), telah dijalankan di ladang. Kajian-kajian

lain (ii, iii, dan v) telah dijalankan di rurnahkaca.

xv

Empat tan metrik kapur GML sehektar telah mengurangkan ketepuan

AI daripada 82% ke paras < 20%. Keadaan ini meningkatkan hasil berat

kering kacang tanah cv. V13 26% dan jagung 71% dibandingkan dengan hasil

daripada petak kawalan tanpa kapur. Pengapuran juga meningkatkan

sumbangan N daripada kacang tanah sebanyak 44 kg N ha-1 yang boleh

digunakan sebagai baja organik (i).

Kacang tanah kultivar cv. V13 dan Bradyrhizobium CB756 adalah

kombinasi terbaik yang dipilih (ii) dan didapati sesuai untuk meningkatkan lagi

hasil dan timbunan N dalam sisa kacang tanah pada keadaan tanah tanpa kapur

dan yang berkapur. Sumbangan N daripada sisa kacang tanah adalah lebih

kurang 77 kg N ha-1 di bawah keadaan tanpa kapur dan 105 kg N ha-1

berkapur, iaitu peningkatan lebih dua kali ganda daripada anggaran yang

didapati daripada keadaan semulajadi dalam kajian di ladang (i). Anggaran

yang dikaji adalah tinggi kerana ianya di bawah keadaan sistem tertutup (ii).

Di kawasan ladang, selain pada keadaan di musim pertama tahun 1981,

kombinasi ini (kacang tanah cv. V13-Bradyrhizobium CB756) menyumbangkan

purata sebanyak 51 kg N ha-1 daripada sistem tanaman giliran LMLM,

manakala sistem MLLM menyumbangkan timbunan N sebanyak 106 kg ha-1

untuk edaran tanaman pertama dan 102 kg ha-1 untuk edaran kedua dalam

jangkamasa empat tahun (1981-1984). Dalam jangkamasa yang sama,

sumbangan daripada kacang tanah yang ditanam tiga kali berturut-turut sebelum

jagung (LLLM), timbunan N daripada sisa kacang tanah ialah 142 kg N ha-1

XVI

untuk edaran pertama (1981-1982) dan 165 kg N ha-1 untuk edaran tanaman

kedua (1983-1984).

Tanaman jagung mengambil 31 % daripada N berasal daripada sisa

kacang tanah dalam sistem LMLM, manakala 21 % di peringkat edaran tanaman

pertama dan 25% di peringkat edaran tanaman kedua. Pengambilan sebanyak

3 1 % terdapat di peringkat edaran tanaman pertama dan 37% daripada edaran

kedua di bawah sistem LLLM. Persamaan baja N sebanyak 56 kg N ha-1 yang

dianggarkan daripada keluk gerakbalas pengambilan N dari percubaan kadar

pembajaan N, adalah mencukupi 35% daripada keperluan N untuk jagung (159

kg N ha-1) di kawasan tanah Ultisol yang dikapurkan.

Bahan kimia selain daripada kapur tidak mempengaruhi/memperbaiki

keasidan tanah atau meningkat hasil kacang tanah. Tetapi CaS04 dan K2S04

menurunkan paras ketepuan AI dan meningkatkan hasil berat kering bahagian

atas kacang tanah 30 hari selepas ditanam (v).

Sementara itu, kapur GML mengekalkan pH tanah di paras 5.5.

Keadaan ini menurunkan ketepuan AI ke tahap 15 % dan meningkatkan hasil

dan sumbangan N kepada tanaman jagung. Di bawah keadaan di ladang, cuma

kacang tanah ditanam tiga kali berturut-turut, menyumbangkan lebih kurang

satu per tiga daripada keperluan N untuk mendapatkan hasil maksimum jagung

sebanyak 6.4 mt ha-1.

XVll

CHAPTER ONE

INTRODUCTION

The acidic nature of Oxisols and Ultisols is an important consideration

in a rubber and oil palm replanting programme in Malaysia although it does not

limit the productivity of these main crops. These two perennial species are

extremely well adapted to high extractable soil aluminium (AI) levels. The

plantation system, however, relies on a low input soil management technology

which includes the chemical fertilizers and symbiotically-fixed N from legume

interrows (cover crops). These legume interrows are replaced by relatively less

acid tolerant legume and non-legume annual food crops during the early phase

of a replanting programme. An extensive area, about 1Z0,000 ha of the highly

weathered Oxisols and Ultisols are utilized for replanting each year.

In the annual cropping system for food legume production AI toxicity is

one of the major soil-related constraints (Foster et at., 1980). This toxicity along

with the low supply of native soil-N limit the productivity of Oxisols and Ultisols

when these soils are cropped to cereals such as maize. The NZ fixing capacity

and yield potential of grain legumes, such as groundnut, on such soils during the

early phase of a replanting programme, however, have not been exploited

although some related studies using soybean and siratro under simulated tropical

environment have shown their potential to enrich the soil (Yaacob and Blair,

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1979, 1980). Among the grain legumes groundnut has the capacity to fix large

quantities of atmospheric N and leave residual N equivalent to 20-60 kg N ha-1

per season (Jones, 1974; Giri and De, 1980; MacColl, 1989b). Some groundnut

cultivars are tolerant of soil acidity but they require relatively high Ca supply

(Munns, 1977). An increase in groundnut yield on soils where this crop has not

been previously grown can be achieved through inoculation with effective

Bradyrhizobium strains (Burton, 1976; Nambiar and Dart, 1983). Consequently,

research on Bradyrhizobium selection for groundnut to maximize N2 fixation and

increase yield under acid soil conditions in Malaysia is necessary. Acidity factors

also significantly influence symbiotic growth of legumes (Andrew, 1978; Carvalho

et at. , 1981 ; Shamsuddin, 1987); these effects on groundnut warrant further

research. Although lime enhanced symbiotic growth of legume through the

neutralization of Al, the optimum rate required by groundnut for maximum

growth and N2 fixation under field conditions is not fully known. Solution

culture studies have shown that Al toxicity in soybean at 20-22 Jl.M La Almana

can be reduced by the inclusion of 15,000 Jl.M Ca (Alva et at. , 1986). However,

Shamsuddin and Kasran (1989) indicated that excess Ca supply (5000 Jl.M Ca)

was antagonistic to uptake of Mg and reduced nodulation in groundnut. It has

been suggested that the protective action of Ca can also be extended to other

cations, such as K, Mg and NH4, which may have similar effects reducing Al

toxicity.

A series of field and pot studies were undertaken to test the hypothesis

that intensive cropping of a selected groundnut cultivar inoculated with a

compatible and highly effective Bradyrhizobium strain could substantially

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contribute N to the succeeding cereal crop, after being cropped several times in

various crop sequence on a limed-amended Ultisol.

In testing this hypothesis, a part of the earlier study by Yaacob and Blair

(1979) was extended to the field situation where the following aspects were

investigated :

i) the amount of lime required to reduce the high toxic AI level

(82%) in an Ultisol for satisfactory growth and yield of

uninoculated local groundnut cultivar and maize (Experiment 1),

ii) selection of appropriate Bradyrhizobium-groundnut combination

on unlimed and limed Ultisol for maximum yield and legume-N

return to the soil (Experiment 2 and 3),

iii) the amount of legume-N returned to soil by selected

Bradyrhizobium-groundnut combination on limed Ultisol receiving

varying amounts of legume-N (Experiment 4),

iv) the increase in the yield of maize (M) grown on limed soil from

inclusion of groundnut (L) inoculated with selected

Bradyrhizobium planted before or after maize in three sequence

(LMLM, MLLM and LLLM) in the rotational crop system

(Experiment 4), and

v) the alleviation of soil acidity by chemicals other than lime

(Experiment 5).

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For investigating (i) a short preliminary experiment and for (iv) a long

term (4 years) experiment were carried out under actual field conditions, at

Puchong Farm, UPM, Malaysia. All other experiments were carried out in the

glasshouse.

CHAPTER 1WO

REVIEW OF LITERATURE

Ultisols

Ultisols are soils with an argillic or kandic horizon and less than 35%

base saturation (at pH 8.2) in the subsoil (Soil Survey Staff, 1975). They are

usually deep, well-drained red or yellow soils with less desirable physical

properties and relatively low inherent fertility. These soils are most extensive

in warm humid climates (749 million ha) that have a seasonal deficit of

precipitation and can be formed from a wide variety of parent materials.

Kaolin, gibbsite and aluminium-interlayered clays are common minerals in the

clay fraction. In Ultisols of tropical America (320 million ha), deficiencies of

N and P are the most limiting soil chemical characteristics. Other soil limiting

factors include deficiencies of K, S, Ca, Mg, Zn and Cu, AI toxicity, P fixation,

and low CEC (Sanchez and Cochrane, 1980; Sanchez and Salinas, 1981).

Similar soil fertility problems also occur in Ultisols of Southeast Asia (Dent,

1980). In Malaysia most of the upland soils with good drainage are Ultisols

which belong to two common great groups: Tropudults and Paleudults. The

common series of Ultisols in Malaysia are the Rengam and Bungor

(Paramananthan, 1978).

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The Bungor series is a member of the clayey, kaolinitic, isohyperthermic

family of the Typic Paleudults. They have a thick argillic horizon which has a

low base status and the clay content does not decrease significantly within 1.5

m of the surface. According to the F AO/UNESCO Legend for the Soil Map

of the World, Bungor series will be classified as Dystric Nitosols (FAO, 1976).

They are characterized by dark grayish brown A horizon with fine sandy loam

texture and deep B horizon having brownish yellow to yellowish brown colours

and fine sandy clay texture. Soil consistency is friable and becomes firmer with

depth. Weak to moderate medium and fine subangular blocky structures are

found in such soils. Few medium to coarse distinct red mottles usually appear

at depths below 100 cm. At depths below 150 cm the colours become paler.

This soil is developed over interbedded sandstones and shales or sandy shales.

They have been mapped over a wide range of terrain ranging from gently

undulating to steep, the commonest being undulating to hilly.

The Bungor series is fairly well distributed in Peninsular Malaysia. It has

been mapped in Perak, Selangor, Negeri Sembilan, lohore, Malacca, Pahang,

Terengganu and Kelantan. Their extent is, however, not known since the semi

detailed soil survey of Malaysia is yet to be completed. The soils are usually

well-drained, have a good permeability, and are planted with a variety of crops

including rubber, oil palm, fruit trees, and cocoa although such soils poses

limitations of AI toxicity to annual crops such as maize and groundnut. Some

of these areas are still under primary forest vegetation.

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Soil Factors Limiting Plant Growth

Soil reaction (pH) may affect plant growth and development by its

influence on the availability of certain essential elements. The sorption and

precipitation of phosphates is increased in acid soils with high concentrations

of Fe and Al, such as the Bungor series. A decrease in soil pH results in Mo

being reduced in the soils. Acid mineral soils are usually high in soluble Al

and Mn and excessive amounts of these elements are toxic to plants. Although

the solubility of Fe3 + is low in well-aerated acid soils, iron oxides can still

have a major role in the reversion of fertilizer phosphorus.

Aluminium toxicity is the most important growth-limiting factor in many

acid soils, particularly those having pH levels below 5.0 which are commonly

found in many Malaysian soils (Law and Tan, 1975). Poor growth of plants in

acid soils has been associated with the high concentration of Al in the soil

solution (Evan and Kamprath, 1970; Friesen et at., 1980). The exchangeable

and solution Al are closely correlated with pH (Adams and Lund, 1966;

Kamprath, 1970; 1978). Al toxicity affects the yield of sensitive species as the

pH is lowered to 5.0 (Al solution concentration, 20 J.l.M) and 4.5 for the

tolerant species (Al solution concentration, 60 J.l.M) (Adam, 1978; Helyar, 1978;

Munns, 1978). The epipedons of Oxisols and Ultisols are generally dominated

by exchangeable Al (IBSRAM, 1984). According to Kamprath ( 1980), crop

production is drastically reduced when Al saturation of the active cation

exchange sites is greater than 60%, which is associated with the toxic level of

Al in solution ( > 0.1 mmol( + )L-1), and it tends to be optimum when this

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