Abstract
Abstract Supplying nitrogen (N) to crops by incorporating N 2 -fixing green manures into soil can improve soil functioning and increase soil carbon storage. However, as with N-fertiliser use, excess mineral N from decomposed green manures can be lost via leaching as NO 3 − and emitted as the greenhouse gas N 2 O. To improve nitrogen use efficiency (NUE) we propose supplying leaf matter harvested from permanent stands of N 2 -fixing plants grown ex-situ as perennial mobile green manures (PMGMs), thus allowing flexible timing of additions to synchronise with N demand. To assess the effectivity of PMGM use, we monitored crop N uptake, biomass production and soil mineral N from fertilisation by three potential PMGM species, Alnus glutinosa (alder), Gunnera tinctoria (gunnera), and Ulex europaeus (gorse), compared to the conventional green manure Trifolium pratense (red clover) and NH 4 NO 3 fertiliser. Effectivity of N fertilisation by PMGMs increased with the duration of their use. In the first season of a field experiment, crop N uptake after addition of 200 kg N ha −1 within gunnera was equivalent to that from only 14 kg NH 4 NO 3 -N ha −1 , but after two yearly harvests with annual gunnera additions it increased to 70 kg NH 4 NO 3 -N ha −1 year −1 equivalent. In a 1-year pot experiment, PMGMs resulted in equal or higher crop biomass than clover-fed crops, with lower soil NO 3 − (≤ 25 mg N L −1 soil solution) than in clover-treated soil (≥ 130 mg N L −1 ). We conclude that PMGMs have potential to increase NUE over that of traditional green manures and discuss the feasibility and possible agro-ecological benefits of PMGM-fed systems.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 6
Claim · model-written summary
Effectiveness of perennial mobile green manure increased with duration of use.
Verbatim
e0“Effectivity of N fertilisation by PMGMs increased with the duration of their use.”
t0“Supplying nitrogen (N) to crops by incorporating”
Claim · model-written summary
First-season crop nitrogen uptake after gunnera addition equalled that from 14 kg ammonium nitrate nitrogen per hectare.
Verbatim
e0“crop N uptake after addition of 200 kg N ha −1 within gunnera was equivalent to that from only 14 kg NH 4 NO 3 -N ha −1”
Claim · model-written summary
After two annual gunnera additions, crop nitrogen uptake rose to a 70 kg ammonium nitrate nitrogen equivalent.
- Taxon
- cropt0
- Treatment
- annual gunnera additionse0
- Outcome
- N uptaket1
- Direction
- increasede0
- Value
- 70 kg NH 4 NO 3 -N ha −1 year −1e0
Not reportedComparator
Verbatim
e0“after two yearly harvests with annual gunnera additions it increased to 70 kg NH 4 NO 3 -N ha −1 year −1 equivalent”
t0“crop N uptake after addition of 200 kg N ha −1”
t1“crop N uptake after addition of 200 kg N ha −1”
Claim · model-written summary
Perennial mobile green manures gave equal or higher crop biomass than clover.
Verbatim
e0“PMGMs resulted in equal or higher crop biomass than clover-fed crops”
t0“Supplying nitrogen (N) to crops by incorporating”
Claim · model-written summary
Perennial mobile green manures produced lower soil nitrate than clover.
- Treatment
- PMGMse1
- Outcome
- soil NO 3 −e0
- Direction
- lowere0
- Value
- ≤ 25 mg N L −1 soil solutione0
- Qualifier
- ≥ 130 mg N L −1e0
- Comparator
- clover-treated soile0
Not reportedTaxon
Verbatim
e0“with lower soil NO 3 − (≤ 25 mg N L −1 soil solution) than in clover-treated soil (≥ 130 mg N L −1 )”
t0“perennial mobile green manures”
e1“Effectivity of N fertilisation by PMGMs increased with the duration of their use.”
Claim · model-written summary
The authors conclude that perennial mobile green manures could increase nitrogen use efficiency over traditional green manures.
Verbatim
e0“We conclude that PMGMs have potential to increase NUE over that of traditional green manures”
t0“Supplying nitrogen (N) to crops by incorporating”
e1“nitrogen use efficiency (NUE)”