Abstract
Onion ( Allium cepa ) and tropical pumpkin ( Cucurbita moschata ) combined contribute 13% of the total gross agricultural income (GAI) for vegetable crops in Puerto Rico, which is estimated at $54.5 million. Both crops are usually rotated on an annual basis. In this study, an onion-tropical pumpkin rotation was used to test the effect of fertilizer-nitrogen (N) on agronomic indicators of onion (plant height, number of leaves per plant, leaf color index, and leaf nutrient concentration), yield of both onion and tropical pumpkin, and inorganic N changes in the soil profile. Three fertilizer-N levels (140, 196, 252 kg·ha −1 ) were applied to onion, followed by 112 and 280 kg·ha −1 of N applied to tropical pumpkin. For tropical pumpkin, N was applied in plots with the lowest and highest fertilizer-N levels from the previous onion crop. Changes in onion agronomic indicators with increasing N fertilization were either not significant or showed no clear trend. There was no increase in total and marketable yields and number of onions with increasing fertilizer-N levels. Tropical pumpkin yields significantly increased with 280 kg·ha −1 compared with 112 kg·ha −1 of N. Using 112 kg·ha −1 as a baseline fertilizer-N application, the value/cost ratio for tropical pumpkin was $12.70 per dollar of fertilizer-N. In low fertilizer-N plots, immediately available inorganic soil N (0 to 30 cm) did not change between the onion and tropical pumpkin crop, but then decreased at the end of the rotation. In high fertilizer-N plots, immediately available soil N greatly increased after onion, but then decreased at the end of the rotation. Potentially leachable soil N (30 to 100 cm) also increased after the onion crop and then decreased after pumpkin. However, in high fertilizer-N plots, potentially leachable soil N remained 44% higher at the end, compared with the beginning, of the rotation. The increased income attainable with the highest fertilizer-N in tropical pumpkin may be offset by greater residual soil N in the lower part of the soil profile, and the potential for this N to have a negative environmental impact.
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Claims 9
Claim · model-written summary
Onion agronomic indicators had no clear or significant trend with increasing N.
- Taxon
- onion
Allium cepae0 - Treatment
- increasing N fertilizatione0
- Outcome
- onion agronomic indicatorse0
- Direction
- no clear trende0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes in onion agronomic indicators with increasing N fertilization were either not significant or showed no clear trend.”
Claim · model-written summary
Increasing fertilizer N did not increase onion total and marketable yields or number.
- Taxon
- onionsAllium cepae0
- Treatment
- increasing fertilizer-N levelse0
- Outcome
- total and marketable yields and number of onionse0
- Direction
- no increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was no increase in total and marketable yields and number of onions with increasing fertilizer-N levels.”
Claim · model-written summary
Pumpkin yields increased significantly at 280 versus 112 kg per hectare N.
Verbatim
e0“Tropical pumpkin yields significantly increased with 280 kg·ha −1 compared with 112 kg·ha −1 of N.”
Claim · model-written summary
Pumpkin fertilizer N returned $12.70 per fertilizer dollar at the baseline rate.
Verbatim
e0“Using 112 kg·ha −1 as a baseline fertilizer-N application, the value/cost ratio for tropical pumpkin was $12.70 per dollar of fertilizer-N.”
Claim · model-written summary
Low-N plots showed unchanged available topsoil N between crops, then a decrease at rotation end.
Verbatim
e0“In low fertilizer-N plots, immediately available inorganic soil N (0 to 30 cm) did not change between the onion and tropical pumpkin crop, but then decreased at the end of the rotation.”
Claim · model-written summary
High-N plots had sharply increased available soil N after onion and a decrease at rotation end.
- Taxon
- onionAllium cepae0
- Outcome
- immediately available soil Ne0
- Direction
- greatly increasede0
- Qualifier
- high fertilizer-N plotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In high fertilizer-N plots, immediately available soil N greatly increased after onion, but then decreased at the end of the rotation.”
Claim · model-written summary
Potentially leachable soil N rose after onion then fell after pumpkin.
- Taxon
- onionAllium cepae0
- Outcome
- Potentially leachable soil N (30 to 100 cm)e0
- Direction
- increasede0
- Qualifier
- after the onion crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Potentially leachable soil N (30 to 100 cm) also increased after the onion crop and then decreased after pumpkin.”
Claim · model-written summary
In high-N plots, leachable soil N remained 44% above the rotation start.
- Taxon
- onionAllium cepat0
- Outcome
- potentially leachable soil Ne0
- Direction
- highere0
- Value
- 44%e0
- Qualifier
- high fertilizer-N plotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in high fertilizer-N plots, potentially leachable soil N remained 44% higher at the end, compared with the beginning, of the rotation.”
t0“Onion”
Claim · model-written summary
Higher pumpkin income may be offset by residual deep-soil N and environmental impact.
Verbatim
e0“The increased income attainable with the highest fertilizer-N in tropical pumpkin may be offset by greater residual soil N in the lower part of the soil profile, and the potential for this N to have a negative environmental impact.”
The same questions in other papers
fertilization · quality: postharvest · Allium cepa (onion)Positive and negative results
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See all 69 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.