Abstract
Potassium fertilization recommendations for alfalfa ( Medicago sativa L.) vary depending on the area of production, soil levels, and crop management. The objectives of this study were to determine the impact of K fertilization on irrigated alfalfa yield, yield components, and soil exchangeable K (K e ) values in a Mediterranean climate. A field experiment was conducted during a period of 4 yr (2002–2006) in Spain, on a soil with moderate levels of K e (161 mg K kg −1 ). The treatments applied were five annual rates of K (0, 100, 200, 300, and 400 kg K ha −1 ). Total 4‐yr dry matter (DM) yields averaged 74.9 Mg ha −1 without differences between K fertilizer rates, although the unfertilized control produced the lowest DM yields. The 4‐yr crop uptake of K reached 1738 kg ha −1 with the application of 400 kg K ha −1 yr −1 , and 756 kg K ha −1 for the 0 K fertilization. The removal was greater than the K applied. The results suggest that large amounts of K should not be applied to alfalfa because the crop uses excess K without increasing yield. Soil K e concentrations decreased every year for all K rates except for the highest treatment of 400 kg K ha −1 yr −1 . Lack of K fertilization did not affect stand density but the shoot weight was the yield component most closely related to K fertilization.
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Claims 9
Claim · model-written summary
Four-year dry matter yield averaged 74.9 Mg ha−1 with no differences among K rates.
- Taxon
- Alfalfa
Medicago sativat0 - Treatment
- K fertilizer ratese0
- Outcome
- dry matter (DM) yieldse0
- Direction
- without differencese0
- Value
- 74.9 Mg ha −1e0
- Setting
- Spaine1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total 4‐yr dry matter (DM) yields averaged 74.9 Mg ha −1 without differences between K fertilizer rates, although the unfertilized control produced the lowest DM yields.”
t0“Alfalfa”
e1“in Spain”
Claim · model-written summary
The unfertilized control had the lowest dry matter yield.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- unfertilizede0
- Outcome
- DM yieldse0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“although the unfertilized control produced the lowest DM yields.”
t0“Alfalfa”
Claim · model-written summary
Four-year K uptake reached 1738 kg ha−1 at the highest K rate.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- 400 kg K ha −1 yr −1e0
- Outcome
- crop uptake of Ke0
- Value
- 1738 kg ha −1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The 4‐yr crop uptake of K reached 1738 kg ha −1 with the application of 400 kg K ha −1 yr −1 , and 756 kg K ha −1 for the 0 K fertilization.”
t0“Alfalfa”
Claim · model-written summary
Four-year K uptake was 756 kg ha−1 without K fertilization.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- 0 K fertilizatione0
- Outcome
- crop uptake of Ke0
- Value
- 756 kg K ha −1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The 4‐yr crop uptake of K reached 1738 kg ha −1 with the application of 400 kg K ha −1 yr −1 , and 756 kg K ha −1 for the 0 K fertilization.”
t0“Alfalfa”
Claim · model-written summary
Crop K removal exceeded applied K.
- Taxon
- AlfalfaMedicago sativat0
- Outcome
- removale0
- Direction
- greatere0
- Comparator
- K appliede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The removal was greater than the K applied.”
t0“Alfalfa”
Claim · model-written summary
The authors advise against large K applications because excess uptake does not increase yield.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- large amounts of K should not be appliede0
- Qualifier
- the crop uses excess K without increasing yielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The results suggest that large amounts of K should not be applied to alfalfa because the crop uses excess K without increasing yield.”
Claim · model-written summary
Soil exchangeable K decreased annually except under the highest K rate.
- Treatment
- all K ratese0
- Outcome
- Soil K e concentrationse0
- Direction
- decreasede0
- Qualifier
- except for the highest treatment of 400 kg K ha −1 yr −1e0
Not reportedTaxonComparator
Verbatim
e0“Soil K e concentrations decreased every year for all K rates except for the highest treatment of 400 kg K ha −1 yr −1 .”
Claim · model-written summary
Lack of K fertilization did not affect stand density.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- Lack of K fertilizatione0
- Outcome
- stand densitye0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lack of K fertilization did not affect stand density but the shoot weight was the yield component most closely related to K fertilization.”
t0“Alfalfa”
Claim · model-written summary
Shoot weight was the yield component most closely associated with K fertilization.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- K fertilizatione0
- Outcome
- shoot weighte0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the shoot weight was the yield component most closely related to K fertilization.”
t0“Alfalfa”
The same questions in other papers
fertilization · growth · Medicago sativa (alfalfa)Results differ
17 papers in the same direction as this paper · 71 in the opposite direction
- positive
- positive
- positive
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See all 89 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.