Abstract
The summer maize yields and partial factor productivity of nitrogen (N) fertilizer (PFPN, grain yield per unit N fertilizer) on smallholder farms in China are low, and differ between farms due to complex, sub-optimal management practices. We collected data on management practices and yields from smallholder farms in three major summer maize-producing sites—Laoling, Quzhou and Xushui—in the North China Plain (NCP) for two growing seasons, during 2015–2016. Boundary line analysis and a Proc Mixed Model were used to evaluate the contribution of individual factors and their interactions. Summer maize grain yields and PFPN ranged from 6.6 t ha−1 to 14.2 t ha−1 and 15.4 kg kg−1 to 96.1 kg kg−1, respectively, and averaged 10.5 t ha−1 and 49.1 kg kg−1, respectively. The mean total yield gap and PFPN gap were 3.6 t ha−1 and 43.3 kg kg−1 in Laoling, 2.2 t ha−1 and 24.5 kg kg−1 in Xushui, and 2.8 t ha−1 and 41.1 kg kg−1 in Quzhou. A positive correlation was observed between the yield gap and PFPN gap; the PFPN gap could be reduced by 6.0 kg kg−1 (3.6–6.6 kg kg−1) by reducing the yield gap by 1 t ha−1. The high yield and high PFPN (HH) fields had a higher plant density and lower N fertilization rate than the low yield and low PFPN (LL) fields. Our results show that multiple management factors caused the yield gap, but the relative contribution of plant density is slightly higher than that of other management practices, such as N input, the sowing date, and potassium fertilizer input. The low PFPN was mainly attributed to an over-application of N fertilizer. To enhance the sustainable production of summer maize, the production gaps should be tackled through programs that guide smallholder farmers on the adoption of optimal management practices.
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Claims 12
Claim · model-written summary
Summer maize grain yield ranged from 6.6 to 14.2 t ha−1 and averaged 10.5 t ha−1.
Zea maysNot reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Summer maize grain yields and PFPN ranged from 6.6 t ha−1 to 14.2 t ha−1 and 15.4 kg kg−1 to 96.1 kg kg−1, respectively, and averaged 10.5 t ha−1 and 49.1 kg kg−1, respectively”
t0“Summer Maize”
Claim · model-written summary
PFPN ranged from 15.4 to 96.1 kg kg−1 and averaged 49.1 kg kg−1.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Summer maize grain yields and PFPN ranged from 6.6 t ha−1 to 14.2 t ha−1 and 15.4 kg kg−1 to 96.1 kg kg−1, respectively, and averaged 10.5 t ha−1 and 49.1 kg kg−1, respectively”
t0“Summer Maize”
Claim · model-written summary
Laoling mean yield gap was 3.6 t ha−1 and PFPN gap 43.3 kg kg−1.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mean total yield gap and PFPN gap were 3.6 t ha−1 and 43.3 kg kg−1 in Laoling”
t0“Summer Maize”
Claim · model-written summary
Xushui mean yield gap was 2.2 t ha−1 and PFPN gap 24.5 kg kg−1.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mean total yield gap and PFPN gap were 3.6 t ha−1 and 43.3 kg kg−1 in Laoling, 2.2 t ha−1 and 24.5 kg kg−1 in Xushui”
t0“Summer Maize”
Claim · model-written summary
Quzhou mean yield gap was 2.8 t ha−1 and PFPN gap 41.1 kg kg−1.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mean total yield gap and PFPN gap were 3.6 t ha−1 and 43.3 kg kg−1 in Laoling, 2.2 t ha−1 and 24.5 kg kg−1 in Xushui, and 2.8 t ha−1 and 41.1 kg kg−1 in Quzhou”
t0“Summer Maize”
Claim · model-written summary
Yield gap and PFPN gap were positively correlated.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A positive correlation was observed between the yield gap and PFPN gap”
t0“Summer Maize”
Claim · model-written summary
Reducing yield gap 1 t ha−1 could reduce PFPN gap 6.0 kg kg−1.
- Outcome
- PFPN gape0
- Direction
- reducede0
- Value
- 6.0 kg kg−1e0
- Qualifier
- 3.6–6.6 kg kg−1e0
- Comparator
- yield gap by 1 t ha−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the PFPN gap could be reduced by 6.0 kg kg−1 (3.6–6.6 kg kg−1) by reducing the yield gap by 1 t ha−1”
t0“Summer Maize”
Claim · model-written summary
High yield and PFPN fields had higher plant density than low yield and PFPN fields.
- Material
- high yield and high PFPN (HH) fieldse0
- Outcome
- plant densitye0
- Direction
- highere0
- Comparator
- low yield and low PFPN (LL) fieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high yield and high PFPN (HH) fields had a higher plant density and lower N fertilization rate than the low yield and low PFPN (LL) fields”
t0“Summer Maize”
Claim · model-written summary
High yield and PFPN fields had lower nitrogen fertilizer rates.
- Material
- high yield and high PFPN (HH) fieldse0
- Outcome
- N fertilization ratee0
- Direction
- lowere0
- Comparator
- low yield and low PFPN (LL) fieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high yield and high PFPN (HH) fields had a higher plant density and lower N fertilization rate than the low yield and low PFPN (LL) fields”
t0“Summer Maize”
Claim · model-written summary
Plant density contributed slightly more to the yield gap than other management practices.
- Outcome
- relative contribution of plant densitye0
- Direction
- highere0
- Comparator
- other management practicese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the relative contribution of plant density is slightly higher than that of other management practices, such as N input, the sowing date, and potassium fertilizer input”
t0“Summer Maize”
Claim · model-written summary
Low PFPN was mainly attributed to excess nitrogen fertilizer.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The low PFPN was mainly attributed to an over-application of N fertilizer”
t0“Summer Maize”
Claim · model-written summary
The authors recommend programs to help farmers adopt optimal management practices.
- Outcome
- programs that guide smallholder farmers on the adoption of optimal management practicese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“production gaps should be tackled through programs that guide smallholder farmers on the adoption of optimal management practices”
t0“Summer Maize”