Abstract
SUMMARY Legume crops are not usually fertilised with mineral N. However, there are at least two agronomic cases when it would be advantageous to distribute N fertiliser to legume crops: at sowing, before the onset of nodule functioning, and when a legume is intercropped with a cereal. We highlight the impact of various levels of fertiliser nitrogen on grain yield, nodulation capacity and biological nitrogen fixation in the four most common grain legume crops grown in central Italy. Chickpea ( Cicer arietinum L.), field bean ( Vicia faba L. var. minor), pea ( Pisum sativum L.) and white lupin ( Lupinus albus L.) were grown in soil inside growth boxes for two cropping seasons with five nitrogen fertilisation rates: 0, 40, 80, 120 and 160 kg ha −1 . In both years, experimental treatments (five crops and five levels of N) were arranged in a randomised block design. We found that unfertilised plants overall yielded grain, total biomass and nitrogen at a similar level to plants supplied with 80–120 kg ha −1 of mineral nitrogen. However, above those N rates, the production of chickpea, pea and white lupin decreased, thus indicating that the high supply of N fertiliser decreased the level of N 2 fixed to such an extent that the full N 2 -fixing potential might not be achieved. In all four grain legumes, the amount of N 2 fixed was positively related to nodule biomass, which was inversely related to the rate of the N fertiliser applied. The four grain legumes studied responded differently to N fertilisation: in white lupin and chickpea, the amount of nitrogen derived from N 2 fixation linearly decreased with increasing N supply as a result of a reduction in nodulation and N 2 fixed per unit mass of nodules. Conversely, in field bean and pea, the decrease in N 2 fixation was only due to a reduction in nodule biomass since nodule fixation activity increased with N supply. Our results suggest that the legume species and the N rate are critical factors in determining symbiotic N 2 -fixation responses to N fertilisation.
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Claims 17
Claim · model-written summary
Unfertilized legumes produced similar grain, biomass and nitrogen to legumes at 80–120 kg ha −1 mineral N.
Verbatim
e0“unfertilised plants overall yielded grain, total biomass and nitrogen at a similar level to plants supplied with 80–120 kg ha −1 of mineral nitrogen”
Claim · model-written summary
Above 80–120 kg ha −1 N, chickpea production decreased.
- Taxon
- chickpea
Cicer arietinume0 - Treatment
- above those N ratese0
- Outcome
- productione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“above those N rates, the production of chickpea, pea and white lupin decreased”
Claim · model-written summary
Above 80–120 kg ha −1 N, pea production decreased.
- Taxon
- pea
Lathyrus oleraceuse0 - Treatment
- above those N ratese0
- Outcome
- productione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“above those N rates, the production of chickpea, pea and white lupin decreased”
Claim · model-written summary
Above 80–120 kg ha −1 N, white lupin production decreased.
Not reportedComparator
Verbatim
e0“above those N rates, the production of chickpea, pea and white lupin decreased”
Claim · model-written summary
Nitrogen fixed was positively related to nodule biomass in chickpea.
- Taxon
- chickpeaCicer arietinume1
- Organ / stage
- nodule biomasse0
- Outcome
- amount of N 2 fixede0
- Direction
- positively relatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In all four grain legumes, the amount of N 2 fixed was positively related to nodule biomass”
t0“GRAIN LEGUMES”
e1“Chickpea ( Cicer arietinum L.), field bean ( Vicia faba L. var. minor), pea ( Pisum sativum L.) and white lupin ( Lupinus albus L.)”
Claim · model-written summary
Nitrogen fixed was positively related to nodule biomass in field bean.
Verbatim
e0“In all four grain legumes, the amount of N 2 fixed was positively related to nodule biomass”
t0“GRAIN LEGUMES”
e1“Chickpea ( Cicer arietinum L.), field bean ( Vicia faba L. var. minor), pea ( Pisum sativum L.) and white lupin ( Lupinus albus L.)”
Claim · model-written summary
Nitrogen fixed was positively related to nodule biomass in pea.
- Taxon
- peaLathyrus oleraceuse1
- Organ / stage
- nodule biomasse0
- Outcome
- amount of N 2 fixede0
- Direction
- positively relatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In all four grain legumes, the amount of N 2 fixed was positively related to nodule biomass”
t0“GRAIN LEGUMES”
e1“Chickpea ( Cicer arietinum L.), field bean ( Vicia faba L. var. minor), pea ( Pisum sativum L.) and white lupin ( Lupinus albus L.)”
Claim · model-written summary
Nitrogen fixed was positively related to nodule biomass in white lupin.
Verbatim
e0“In all four grain legumes, the amount of N 2 fixed was positively related to nodule biomass”
t0“GRAIN LEGUMES”
e1“Chickpea ( Cicer arietinum L.), field bean ( Vicia faba L. var. minor), pea ( Pisum sativum L.) and white lupin ( Lupinus albus L.)”
Claim · model-written summary
Nodule biomass was inversely related to nitrogen fertilizer rate across the four legumes.
Verbatim
e0“nodule biomass, which was inversely related to the rate of the N fertiliser applied”
t0“GRAIN LEGUMES”
e1“Chickpea ( Cicer arietinum L.), field bean ( Vicia faba L. var. minor), pea ( Pisum sativum L.) and white lupin ( Lupinus albus L.)”
Claim · model-written summary
Nitrogen from fixation declined linearly with increasing N in white lupin.
Verbatim
e0“in white lupin and chickpea, the amount of nitrogen derived from N 2 fixation linearly decreased with increasing N supply”
Claim · model-written summary
Nitrogen from fixation declined linearly with increasing N in chickpea.
- Taxon
- chickpeaCicer arietinume0
- Treatment
- increasing N supplye0
- Outcome
- amount of nitrogen derived from N 2 fixatione0
- Direction
- linearly decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in white lupin and chickpea, the amount of nitrogen derived from N 2 fixation linearly decreased with increasing N supply”
Claim · model-written summary
Nodule fixation activity increased with nitrogen supply in field bean.
Verbatim
e0“in field bean and pea, the decrease in N 2 fixation was only due to a reduction in nodule biomass since nodule fixation activity increased with N supply”
Claim · model-written summary
Nodule fixation activity increased with nitrogen supply in pea.
- Taxon
- peaLathyrus oleraceuse0
- Treatment
- N supplye0
- Outcome
- nodule fixation activitye0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in field bean and pea, the decrease in N 2 fixation was only due to a reduction in nodule biomass since nodule fixation activity increased with N supply”
Claim · model-written summary
Reduced nodule biomass accounted for decreased fixation in field bean.
Verbatim
e0“in field bean and pea, the decrease in N 2 fixation was only due to a reduction in nodule biomass”
Claim · model-written summary
Reduced nodule biomass accounted for decreased fixation in pea.
- Taxon
- peaLathyrus oleraceuse0
- Organ / stage
- nodule biomasse0
- Outcome
- decrease in N 2 fixatione0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in field bean and pea, the decrease in N 2 fixation was only due to a reduction in nodule biomass”
Claim · model-written summary
Reduced nodulation and fixation per nodule mass explained lower nitrogen fixation in white lupin.
Verbatim
e0“in white lupin and chickpea, the amount of nitrogen derived from N 2 fixation linearly decreased with increasing N supply as a result of a reduction in nodulation and N 2 fixed per unit mass of nodules”
Claim · model-written summary
Reduced nodulation and fixation per nodule mass explained lower nitrogen fixation in chickpea.
- Taxon
- chickpeaCicer arietinume0
- Organ / stage
- nodulese0
- Outcome
- amount of nitrogen derived from N 2 fixatione0
- Direction
- decreasede0
- Qualifier
- as a result of a reduction in nodulation and N 2 fixed per unit mass of nodulese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in white lupin and chickpea, the amount of nitrogen derived from N 2 fixation linearly decreased with increasing N supply as a result of a reduction in nodulation and N 2 fixed per unit mass of nodules”
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See all 102 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.