Paper · 2025 · Frontiers in Soil Science

Residual soil-applied zinc improves grain zinc nutritional quality of maize grown under contrasting soil types in Malawi

Lester Botoman; Patson C. Nalivata; Joseph G. Chimungu; et al.

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Open access · cc-by

Abstract

Introduction A proper understanding of the residual value of zinc (Zn) is essential for sustainable biofortification of food crops. This study hypothesized that Zn applied at rates higher than the current national recommendation would have significant residual benefits on maize productivity and Zn uptake. Methods The residual effects of soil-applied Zn on maize grain Zn concentration and uptake were evaluated at two Malawian agricultural research stations, Chitedze and Chitala, each with Lixisols and Vertisols soil types. The experiment used three Zn fertilizer rates (1, 30, and 90 kg Zn ha -1 ) applied as ZnSO 4 .7H 2 O in the previous season, arranged in a randomized complete block design (RCBD) with 10 replications per site. Maize grain yield, and Zn concentrations in grain and stover were measured at harvest. Data were analyzed to assess crop yield and Zn uptake relative to Zn application rates and soil types. Results Maize grain yield in the second season was 24.6% higher on plots receiving 30 kg Zn ha -1 compared to those with 1 kg Zn ha -1 . Grain Zn concentration and Zn uptake increased by 12.5% and 29.6%, respectively, on plots with 30 kg Zn ha -1 versus the lowest rate. Application of 90 kg Zn ha -1 did not provide additional benefits over 30 kg ha -1 for yield, Zn concentration, or Zn uptake. Residual Zn benefits did not vary between soil types. Discussion These results demonstrate that residual application of 30 kg Zn ha -1 significantly enhances maize productivity and Zn biofortification compared to the current national recommendation of 1 kg Zn ha -1 . Given no added advantage with 90 kg Zn ha -1 , revising Zn fertilizer guidelines to higher but optimized rates could improve the effectiveness of biofortification programs without environmental or economic drawbacks.

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Claims 6

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Residual 30 kg Zn ha -1 increased second season maize grain yield by 24.6% versus 1 kg Zn ha -1.

Taxon
MaizeZea mayse0
Treatment
30 kg Zn ha -1e0
Outcome
grain yielde0
Direction
highere0
Value
24.6%e0
Comparator
1 kg Zn ha -1e0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e0

“Maize grain yield in the second season was 24.6% higher on plots receiving 30 kg Zn ha -1 compared to those with 1 kg Zn ha -1 .”

✓ located verbatim in the source · abstract, characters 936–1064 · show in text ↑
Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Residual 30 kg Zn ha -1 increased grain zinc concentration by 12.5% versus the lowest rate.

Taxon
maizeZea mayst0
Treatment
30 kg Zn ha -1e0
Outcome
Grain Zn concentratione0
Direction
increasede0
Value
12.5%e0
Comparator
lowest ratee0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e0

“Grain Zn concentration and Zn uptake increased by 12.5% and 29.6%, respectively, on plots with 30 kg Zn ha -1 versus the lowest rate.”

✓ located verbatim in the source · abstract, characters 1065–1198 · show in text ↑
t0

“maize”

✓ located verbatim in the source · title, characters 70–75 · show in text ↑
Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Residual 30 kg Zn ha -1 increased Zn uptake by 29.6% versus the lowest rate.

Taxon
maizeZea mayst0
Treatment
30 kg Zn ha -1e0
Outcome
Zn uptakee0
Direction
increasede0
Value
29.6%e0
Comparator
lowest ratee0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e0

“Grain Zn concentration and Zn uptake increased by 12.5% and 29.6%, respectively, on plots with 30 kg Zn ha -1 versus the lowest rate.”

✓ located verbatim in the source · abstract, characters 1065–1198 · show in text ↑
t0

“maize”

✓ located verbatim in the source · title, characters 70–75 · show in text ↑
Intervention effectobservedoriginal resultno effectmeasured

Claim · model-written summary

Residual 90 kg Zn ha -1 gave no extra benefit over 30 kg ha -1 for yield, zinc concentration or zinc uptake.

Taxon
maizeZea mayst0
Treatment
90 kg Zn ha -1e0
Outcome
yield, Zn concentration, or Zn uptakee0
Direction
did not provide additional benefitse0
Comparator
30 kg ha -1e0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e0

“Application of 90 kg Zn ha -1 did not provide additional benefits over 30 kg ha -1 for yield, Zn concentration, or Zn uptake.”

✓ located verbatim in the source · abstract, characters 1199–1324 · show in text ↑
t0

“maize”

✓ located verbatim in the source · title, characters 70–75 · show in text ↑
Associationobservedoriginal resultno effectmeasured

Claim · model-written summary

Residual zinc benefits did not vary between soil types.

Taxon
maizeZea mayst0
Outcome
Residual Zn benefitse0
Direction
did not varye0
Setting
soil typese0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e0

“Residual Zn benefits did not vary between soil types.”

✓ located verbatim in the source · abstract, characters 1325–1378 · show in text ↑
t0

“maize”

✓ located verbatim in the source · title, characters 70–75 · show in text ↑
Recommendationauthor interpretationoriginal resultbasis n/a

Claim · model-written summary

The authors suggest revising zinc fertilizer guidelines to higher optimized rates.

Taxon
maizeZea mayst0
Outcome
revising Zn fertilizer guidelines to higher but optimized ratese0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e0

“revising Zn fertilizer guidelines to higher but optimized rates could improve the effectiveness of biofortification programs”

✓ located verbatim in the source · abstract, characters 1640–1764 · show in text ↑
t0

“maize”

✓ located verbatim in the source · title, characters 70–75 · show in text ↑

zinc atom · nutrient: content · Zea mays (maize)Results differ

235 papers: 199 positive, 36 negative or no effect

198 papers in the same direction as this paper · 33 in the opposite direction · 3 reporting no difference from an alternative

  1. positive
  2. positive
  3. no effect

231 papers more in this group

See all 235 papers →

zinc atom · yield · Zea mays (maize)Results differ

441 papers: 391 positive, 50 negative or no effect

390 papers in the same direction as this paper · 47 in the opposite direction · 3 reporting no difference from an alternative

  1. no effect
  2. positive
  3. positive

437 papers more in this group

See all 441 papers →

Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.