Phosphorus cycling within soil aggregate fractions of a highly weathered tropical soil: A conceptual model

Gina Garland, E. K. Bünemann, A. Oberson, E. Frossard, S. Snapp, R. Chikowo, J. Six

Research output: Research - peer-reviewArticle

Abstract

Effective use of soil phosphorus (P) for crop production requires an understanding of how P pools are stabilized and cycled within soil aggregates, rather than assuming that P dynamics, particularly organic P, closely follow those of C. The main goal of this study was to compare C and N cycling with P dynamics in soil aggregate fractions under two distinct crop species, maize (Zea mays) and pigeon pea (Cajanus cajan) in a highly-weathered Lixisol. We found that while C and N follow an open cycle, whereby C and N are mineralized from microaggregates during macroaggregate turnover and partially exit the soil system as gas and leachate, P has a relatively closed cycle, where most of the mineralized and solubilized P from microaggregates is lost from the plant-available pool via sorption to the unaggregated silt and clay-sized particles (<53 μm). While the above postulated P cycling mechanisms were the same for maize and pigeon pea, P loss from microaggregates and subsequent enrichment of the silt and clay particles was significantly higher in soils under maize compared to pigeon pea (320 and 331 mg P kg−1 lost from occluded microaggregates and gained by free silt and clay particles, respectively, compared to 129 and 97 mg P kg−1 under pigeon pea). This is attributed to the significantly increased soil aggregation under pigeon pea, which led to greater accumulation of P, particularly organic P, in the free microaggregates (77 mg P kg−1 compared to 29 mg P kg−1) and slower rates of macroaggregate turnover. We conclude that increasing soil aggregation can substantially reduce organic P losses from aggregate occluded fractions and its subsequent sorption as inorganic P to silt and clay particles. Thus, P cycling can be improved in tropical cropping systems on highly-weathered soils by introducing crop species that enhance the occlusion of organic P into aggregates.

LanguageEnglish (US)
Pages91-98
Number of pages8
JournalSoil Biology and Biochemistry
Volume116
DOIs
StatePublished - Jan 1 2018

Profile

microaggregates
pigeon peas
tropical soils
soil aggregates
phosphorus
tropical soil
soil aggregate
soil
Phosphorus
Soil
microaggregate
silt
clay
particle
Peas
Columbidae
corn
maize
Zea mays
soil aggregation

Keywords

  • Cajanus cajan
  • Lixisol
  • Phosphorus
  • Soil aggregation
  • Zea mays

ASJC Scopus subject areas

  • Microbiology
  • Soil Science

Cite this

Phosphorus cycling within soil aggregate fractions of a highly weathered tropical soil : A conceptual model. / Garland, Gina; Bünemann, E. K.; Oberson, A.; Frossard, E.; Snapp, S.; Chikowo, R.; Six, J.

In: Soil Biology and Biochemistry, Vol. 116, 01.01.2018, p. 91-98.

Research output: Research - peer-reviewArticle

@article{dfcd1cf6d7b8421b9836c85077f539d7,
title = "Phosphorus cycling within soil aggregate fractions of a highly weathered tropical soil: A conceptual model",
abstract = "Effective use of soil phosphorus (P) for crop production requires an understanding of how P pools are stabilized and cycled within soil aggregates, rather than assuming that P dynamics, particularly organic P, closely follow those of C. The main goal of this study was to compare C and N cycling with P dynamics in soil aggregate fractions under two distinct crop species, maize (Zea mays) and pigeon pea (Cajanus cajan) in a highly-weathered Lixisol. We found that while C and N follow an open cycle, whereby C and N are mineralized from microaggregates during macroaggregate turnover and partially exit the soil system as gas and leachate, P has a relatively closed cycle, where most of the mineralized and solubilized P from microaggregates is lost from the plant-available pool via sorption to the unaggregated silt and clay-sized particles (<53 μm). While the above postulated P cycling mechanisms were the same for maize and pigeon pea, P loss from microaggregates and subsequent enrichment of the silt and clay particles was significantly higher in soils under maize compared to pigeon pea (320 and 331 mg P kg−1 lost from occluded microaggregates and gained by free silt and clay particles, respectively, compared to 129 and 97 mg P kg−1 under pigeon pea). This is attributed to the significantly increased soil aggregation under pigeon pea, which led to greater accumulation of P, particularly organic P, in the free microaggregates (77 mg P kg−1 compared to 29 mg P kg−1) and slower rates of macroaggregate turnover. We conclude that increasing soil aggregation can substantially reduce organic P losses from aggregate occluded fractions and its subsequent sorption as inorganic P to silt and clay particles. Thus, P cycling can be improved in tropical cropping systems on highly-weathered soils by introducing crop species that enhance the occlusion of organic P into aggregates.",
keywords = "Cajanus cajan, Lixisol, Phosphorus, Soil aggregation, Zea mays",
author = "Gina Garland and Bünemann, {E. K.} and A. Oberson and E. Frossard and S. Snapp and R. Chikowo and J. Six",
year = "2018",
month = "1",
doi = "10.1016/j.soilbio.2017.10.007",
volume = "116",
pages = "91--98",
journal = "Soil Biology and Biochemistry",
issn = "0038-0717",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Phosphorus cycling within soil aggregate fractions of a highly weathered tropical soil

T2 - Soil Biology and Biochemistry

AU - Garland,Gina

AU - Bünemann,E. K.

AU - Oberson,A.

AU - Frossard,E.

AU - Snapp,S.

AU - Chikowo,R.

AU - Six,J.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - Effective use of soil phosphorus (P) for crop production requires an understanding of how P pools are stabilized and cycled within soil aggregates, rather than assuming that P dynamics, particularly organic P, closely follow those of C. The main goal of this study was to compare C and N cycling with P dynamics in soil aggregate fractions under two distinct crop species, maize (Zea mays) and pigeon pea (Cajanus cajan) in a highly-weathered Lixisol. We found that while C and N follow an open cycle, whereby C and N are mineralized from microaggregates during macroaggregate turnover and partially exit the soil system as gas and leachate, P has a relatively closed cycle, where most of the mineralized and solubilized P from microaggregates is lost from the plant-available pool via sorption to the unaggregated silt and clay-sized particles (<53 μm). While the above postulated P cycling mechanisms were the same for maize and pigeon pea, P loss from microaggregates and subsequent enrichment of the silt and clay particles was significantly higher in soils under maize compared to pigeon pea (320 and 331 mg P kg−1 lost from occluded microaggregates and gained by free silt and clay particles, respectively, compared to 129 and 97 mg P kg−1 under pigeon pea). This is attributed to the significantly increased soil aggregation under pigeon pea, which led to greater accumulation of P, particularly organic P, in the free microaggregates (77 mg P kg−1 compared to 29 mg P kg−1) and slower rates of macroaggregate turnover. We conclude that increasing soil aggregation can substantially reduce organic P losses from aggregate occluded fractions and its subsequent sorption as inorganic P to silt and clay particles. Thus, P cycling can be improved in tropical cropping systems on highly-weathered soils by introducing crop species that enhance the occlusion of organic P into aggregates.

AB - Effective use of soil phosphorus (P) for crop production requires an understanding of how P pools are stabilized and cycled within soil aggregates, rather than assuming that P dynamics, particularly organic P, closely follow those of C. The main goal of this study was to compare C and N cycling with P dynamics in soil aggregate fractions under two distinct crop species, maize (Zea mays) and pigeon pea (Cajanus cajan) in a highly-weathered Lixisol. We found that while C and N follow an open cycle, whereby C and N are mineralized from microaggregates during macroaggregate turnover and partially exit the soil system as gas and leachate, P has a relatively closed cycle, where most of the mineralized and solubilized P from microaggregates is lost from the plant-available pool via sorption to the unaggregated silt and clay-sized particles (<53 μm). While the above postulated P cycling mechanisms were the same for maize and pigeon pea, P loss from microaggregates and subsequent enrichment of the silt and clay particles was significantly higher in soils under maize compared to pigeon pea (320 and 331 mg P kg−1 lost from occluded microaggregates and gained by free silt and clay particles, respectively, compared to 129 and 97 mg P kg−1 under pigeon pea). This is attributed to the significantly increased soil aggregation under pigeon pea, which led to greater accumulation of P, particularly organic P, in the free microaggregates (77 mg P kg−1 compared to 29 mg P kg−1) and slower rates of macroaggregate turnover. We conclude that increasing soil aggregation can substantially reduce organic P losses from aggregate occluded fractions and its subsequent sorption as inorganic P to silt and clay particles. Thus, P cycling can be improved in tropical cropping systems on highly-weathered soils by introducing crop species that enhance the occlusion of organic P into aggregates.

KW - Cajanus cajan

KW - Lixisol

KW - Phosphorus

KW - Soil aggregation

KW - Zea mays

UR - http://www.scopus.com/inward/record.url?scp=85031284148&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85031284148&partnerID=8YFLogxK

U2 - 10.1016/j.soilbio.2017.10.007

DO - 10.1016/j.soilbio.2017.10.007

M3 - Article

VL - 116

SP - 91

EP - 98

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

SN - 0038-0717

ER -