Abstract
Appropriate nitrogen (N) fertilization and planting density management are critical for efficient production of grain maize ( Zea mays L. ) and for environmental protection. However, the optimal N fertilization and planting density is still not established for forage maize that is cultivated to promote its vegetative growth and utilized for the above-ground vegetative mass. A two-year field experiment was conducted in the rainfed semiarid region of the Chinese Loess Plateau during the 2021 and 2022 growing seasons. The effects of N application rates and planting densities on the dry matter yields and the water- and N-use efficiencies of forage maize were studied. The experiment includes four N application rates (0, 90, 180, and 270 kg ha −1 ) and three plant densities (70000, 90000, and 110000 plants ha −1 ), covering the conventional practices of local farmers. The treatments were organized in a randomized complete block design with four replications. Averaged over the three plant densities, N application rate of 180 kg ha −1 resulted in the maximum average aboveground dry matter yield (18.6 t ha −1 ), crop N accumulation (228.5 kg ha −1 ), dry matter water productivity (51.9 kg ha −1 mm −1 ), and dry matter precipitation productivity (62.9 kg ha −1 mm −1 ) over the two years. Moreover, increasing N application rates significantly increased the soil nitrate-N accumulation (0–200 cm) but reduced the partial factor productivity of applied N fertilizer. Across the three plant densities, the two-year average soil nitrate-N accumulation was 12.6, 32.1, and 75.7 % higher with 90, 180, and 270 kg N ha −1 compared to no N treatment, respectively. The highest soil nitrate accumulation under 270 kg ha −1 N application rate in 2021 (229.5 kg ha −1 ) and in 2022 (329.7 kg ha −1 ) may cause severe nitrate leaching loss and potential soil water contamination, driven by intensive rainfalls. Averaged over the four N rates, planting density of 110000 plants ha −1 increased the crop N accumulation and PFP by 21.2 % and 15.8 % in 2021, compared to 70000 plants ha −1 , respectively. The interaction of N application and planting density significantly affected the aboveground dry matter yield, crop water consumption, dry matter precipitation productivity, and crop N accumulation in 2021, but the effect was non-significant in 2022. Based on these findings, application of 180 kg N ha −1 and planting density of 110000 plants ha −1 are suggested as an efficient management strategy for improving productivity of forage maize and soil water and N resources utilization in the arid region of the Loess Plateau and similar areas. • Effect of plant density on yield and resource use was less than that of N rate. • Dry matter yield and water productivity peaked at 180 kg∙ha −1 N rate. • N application of 270 kg∙ha −1 significantly increased soil nitrate-N accumulation. • Increased N application reduced the partial factor productivity of applied N. • N rate of 180 kg∙ha −1 and density of 110,000 plants∙ha −1 maintained efficient water-and N-use.
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Claims 14
Claim · model-written summary
Increasing N application rates significantly increased soil nitrate-N accumulation (0–200 cm) under forage maize.
- Taxon
- forage maizet0
- Treatment
- increasing N application ratese1
- Outcome
- soil nitrate-N accumulation (0–200 cm)e1
- Direction
- significantly increasede1
Not reportedComparator
Verbatim
e1“increasing N application rates significantly increased the soil nitrate-N accumulation (0–200 cm) but reduced the partial factor productivity of applied N fertilizer”
t0“forage maize in a rainfed region”
Claim · model-written summary
Increasing N application rates reduced the partial factor productivity of applied N fertilizer for forage maize.
- Taxon
- forage maizet0
- Treatment
- increasing N application ratese1
- Outcome
- partial factor productivity of applied N fertilizere1
- Direction
- reducede1
Not reportedComparator
Verbatim
e1“increasing N application rates significantly increased the soil nitrate-N accumulation (0–200 cm) but reduced the partial factor productivity of applied N fertilizer”
t0“forage maize in a rainfed region”
Claim · model-written summary
Averaged over three plant densities, 90 kg N ha −1 raised two-year average soil nitrate-N accumulation by 12.6 % relative to no N.
Verbatim
e2“the two-year average soil nitrate-N accumulation was 12.6, 32.1, and 75.7 % higher with 90, 180, and 270 kg N ha −1 compared to no N treatment, respectively”
t0“forage maize in a rainfed region”
Claim · model-written summary
Averaged over three plant densities, 180 kg N ha −1 raised two-year average soil nitrate-N accumulation by 32.1 % relative to no N.
Verbatim
e2“the two-year average soil nitrate-N accumulation was 12.6, 32.1, and 75.7 % higher with 90, 180, and 270 kg N ha −1 compared to no N treatment, respectively”
t0“forage maize in a rainfed region”
Claim · model-written summary
Averaged over three plant densities, 270 kg N ha −1 raised two-year average soil nitrate-N accumulation by 75.7 % relative to no N.
Verbatim
e2“the two-year average soil nitrate-N accumulation was 12.6, 32.1, and 75.7 % higher with 90, 180, and 270 kg N ha −1 compared to no N treatment, respectively”
t0“forage maize in a rainfed region”
Claim · model-written summary
The highest soil nitrate accumulation under 270 kg ha −1 N in 2021 was 229.5 kg ha −1.
Verbatim
e3“The highest soil nitrate accumulation under 270 kg ha −1 N application rate in 2021 (229.5 kg ha −1 ) and in 2022 (329.7 kg ha −1 ) may cause severe nitrate leaching loss and potential soil water contamination, driven by intensive rainfalls”
t0“forage maize in a rainfed region”
Claim · model-written summary
The highest soil nitrate accumulation under 270 kg ha −1 N in 2022 was 329.7 kg ha −1.
Verbatim
e3“The highest soil nitrate accumulation under 270 kg ha −1 N application rate in 2021 (229.5 kg ha −1 ) and in 2022 (329.7 kg ha −1 ) may cause severe nitrate leaching loss and potential soil water contamination, driven by intensive rainfalls”
t0“forage maize in a rainfed region”
Claim · model-written summary
Intensive rainfall may drive severe nitrate leaching loss and potential soil water contamination under high N.
Verbatim
e4“may cause severe nitrate leaching loss and potential soil water contamination, driven by intensive rainfalls”
t0“forage maize in a rainfed region”
Claim · model-written summary
Averaged over four N rates, planting density of 110000 plants ha −1 increased crop N accumulation by 21.2 % compared with 70000 plants ha −1 in 2021.
Verbatim
e5“Averaged over the four N rates, planting density of 110000 plants ha −1 increased the crop N accumulation and PFP by 21.2 % and 15.8 % in 2021, compared to 70000 plants ha −1 , respectively”
t0“forage maize in a rainfed region”
Claim · model-written summary
Averaged over four N rates, planting density of 110000 plants ha −1 increased partial factor productivity by 15.8 % compared with 70000 plants ha −1 in 2021.
Verbatim
e5“Averaged over the four N rates, planting density of 110000 plants ha −1 increased the crop N accumulation and PFP by 21.2 % and 15.8 % in 2021, compared to 70000 plants ha −1 , respectively”
t0“forage maize in a rainfed region”
Claim · model-written summary
The N-by-density interaction significantly affected aboveground dry matter yield, crop water consumption and dry matter precipitation productivity in 2021.
- Taxon
- forage maizet0
- Treatment
- N application and planting densitye6
- Outcome
- aboveground dry matter yield, crop water consumption, dry matter precipitation productivitye6
- Qualifier
- in 2021e6
Not reportedDirection
Verbatim
e6“The interaction of N application and planting density significantly affected the aboveground dry matter yield, crop water consumption, dry matter precipitation productivity, and crop N accumulation in 2021”
t0“forage maize in a rainfed region”
Claim · model-written summary
The N-by-density interaction significantly affected crop N accumulation in 2021.
- Taxon
- forage maizet0
- Treatment
- N application and planting densitye6
- Outcome
- crop N accumulatione6
- Qualifier
- in 2021e6
Not reportedDirection
Verbatim
e6“The interaction of N application and planting density significantly affected the aboveground dry matter yield, crop water consumption, dry matter precipitation productivity, and crop N accumulation in 2021”
t0“forage maize in a rainfed region”
Claim · model-written summary
The N-by-density interaction had no significant effect on the measured outcomes in 2022.
- Taxon
- forage maizet0
- Treatment
- N application and planting densitye6
- Outcome
- the effecte7
- Qualifier
- in 2022e7
Not reportedDirection
Verbatim
e6“The interaction of N application and planting density significantly affected the aboveground dry matter yield, crop water consumption, dry matter precipitation productivity, and crop N accumulation in 2021”
e7“but the effect was non-significant in 2022”
t0“forage maize in a rainfed region”
Claim · model-written summary
Application of 180 kg N ha −1 with 110000 plants ha −1 is suggested as an efficient management strategy for forage maize.
Verbatim
e1“application of 180 kg N ha −1 and planting density of 110000 plants ha −1 are suggested as an efficient management strategy for improving productivity of forage maize”
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