Abstract
The response of inbred maize (Zea mays L.) lines to nitrogen (N) fertilizer and cowpea (Vigna unguiculata cv. Iron Clay) cover cropping was evaluated in three consecutive croppings from 2014 to 2016 in a Guamaní (Torrifluventic Haplustepts) soil. The crop rotation sequence was maize (spring 2014), cowpea (summer 2014), maize (winter 2014-2015), cowpea (summer 2015), maize (winter 2015-2016) and cowpea (summer 2016). The N fertilizer levels were 0, 90, 135, 180 and 225 kg N/ha for 2014 and 2014-2015 seasons, and 0, 50, 100, 150, and 200 kg N/ha for the 2015-2016 season. Soils were sampled to a depth of 90 cm before and after each successive cropping. Cover crop did not affect maize yields. The effect of N fertilizer on seed yield was observed in two out of the three years with optimum seed yields of 7,034 and 4,708 kg/ha with fertilizer N of 135 and 90 kg N/ha, respectively. Residual soil N tended to increase due to N fertilizer and cover crop. A partial aboveground N budget showed that the net N balance was more positive and increased with each successive fertilizer N level, reaching values of +516 kg N/ha in fallow and +621 kg N/ha with cover crop after three consecutive croppings over a 30-month period. Part of the excess N (not taken up by the crop) was accounted for in the soil profile. A slightly greater positive N balance at higher N fertilizer rates was due to the cover crop rotation. Cover-cropping with cowpea continues to be an important practice that in the long term will result in improved N recycling due to scavenging of residual soil N after maize cropping or by N fixation. Nitrogen fertilizer rates in the range of 90 to 135 kg N/ha can result in good inbred maize yields and can be adjusted with knowledge of soil inorganic N to a depth of 30 cm, that will result in higher yields, improved N use efficiency and reduced losses to the environment.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by-nc. 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 12
Claim · model-written summary
Cowpea cover cropping did not affect maize yield.
- Treatment
- cowpea (Vigna unguiculata cv. Iron Clay) cover croppinge1
- Interactor
- cowpea
Vigna unguiculatae1other - Outcome
- maize yieldse0
- Direction
- did not affecte0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cover crop did not affect maize yields”
e1“cowpea (Vigna unguiculata cv. Iron Clay) cover cropping”
e2“inbred maize (Zea mays L.) lines”
Claim · model-written summary
Fertilizer nitrogen affected seed yield in two of three years.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect of N fertilizer on seed yield was observed in two out of the three years”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
Optimum seed yield was 7,034 kg/ha at 135 kg N/ha fertilizer.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“optimum seed yields of 7,034 and 4,708 kg/ha with fertilizer N of 135 and 90 kg N/ha, respectively”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
Optimum seed yield was 4,708 kg/ha at 90 kg N/ha fertilizer.
- Treatment
- fertilizer N of 135 and 90 kg N/hae0
- Outcome
- seed yieldse0
- Direction
- optimume0
- Value
- 4,708 kg/hae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“optimum seed yields of 7,034 and 4,708 kg/ha with fertilizer N of 135 and 90 kg N/ha, respectively”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
Residual soil nitrogen tended to increase with fertilizer and cover crop.
- Treatment
- N fertilizer and cover crope0
- Outcome
- Residual soil Ne0
- Direction
- increasee0
- Qualifier
- tended toe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Residual soil N tended to increase due to N fertilizer and cover crop”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
Net aboveground nitrogen balance increased with successive fertilizer levels.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the net N balance was more positive and increased with each successive fertilizer N level”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
The fallow nitrogen balance reached +516 kg N/ha.
- Treatment
- fallowe0
- Outcome
- N balancee2
- Value
- +516 kg N/hae0
- Qualifier
- after three consecutive croppings over a 30-month periode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reaching values of +516 kg N/ha in fallow and +621 kg N/ha with cover crop after three consecutive croppings over a 30-month period”
e1“inbred maize (Zea mays L.) lines”
e2“the net N balance was more positive and increased with each successive fertilizer N level”
Claim · model-written summary
The cover crop nitrogen balance reached +621 kg N/ha.
- Treatment
- cover crope0
- Outcome
- N balancee2
- Value
- +621 kg N/hae0
- Qualifier
- after three consecutive croppings over a 30-month periode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reaching values of +516 kg N/ha in fallow and +621 kg N/ha with cover crop after three consecutive croppings over a 30-month period”
e1“inbred maize (Zea mays L.) lines”
e2“the net N balance was more positive and increased with each successive fertilizer N level”
Claim · model-written summary
Some excess nitrogen was found in the soil profile.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Part of the excess N (not taken up by the crop) was accounted for in the soil profile”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
The cover crop rotation gave a slightly greater positive nitrogen balance at higher fertilizer rates.
- Treatment
- cover crop rotatione0
- Outcome
- N balancee0
- Direction
- greatere0
- Qualifier
- higher N fertilizer ratese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A slightly greater positive N balance at higher N fertilizer rates was due to the cover crop rotation”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
The authors recommend cowpea cover cropping for long-term nitrogen recycling.
- Interactor
- cowpeaVigna unguiculatae0other
- Outcome
- Cover-cropping with cowpeae0
- Qualifier
- improved N recyclinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cover-cropping with cowpea continues to be an important practice that in the long term will result in improved N recycling due to scavenging of residual soil N after maize cropping or by N fixation”
e1“inbred maize (Zea mays L.) lines”
Claim · model-written summary
The authors recommend 90 to 135 kg N/ha, adjusted using soil inorganic nitrogen knowledge.
- Outcome
- Nitrogen fertilizer rates in the range of 90 to 135 kg N/hae0
- Qualifier
- knowledge of soil inorganic N to a depth of 30 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer rates in the range of 90 to 135 kg N/ha can result in good inbred maize yields and can be adjusted with knowledge of soil inorganic N to a depth of 30 cm, that will result in higher yields, improved N use efficiency and reduced losses to the environment”
The same questions in other papers
iron atom · yield · Zea mays (maize)Results differ
10 papers in the same direction as this paper · 62 in the opposite direction
- positive
- positive
- positive
69 papers more in this group
See all 73 papers →Vigna unguiculata · yield · Zea mays (maize)Positive and negative results
19 papers in the same direction as this paper · 107 in the opposite direction
- positive
- positive
- positive
123 papers more in this group
See all 127 papers →cover crop · yield · Zea mays (maize)Positive and negative results
117 papers in the same direction as this paper · 104 in the opposite direction
- positive
- positive
- positive
218 papers more in this group
See all 222 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.