Abstract
Sustainable and profitable crop production has become a challenge due to frequent weather extremes, where unstable crop yields are often followed by the negative impacts of agronomic practices on the environment, i.e., nitrate leaching in irrigated and nitrogen (N)-fertilized crop production. To study this issue, a three-year field study was conducted during quite different growing seasons in terms of weather conditions, i.e., extremely wet, extremely dry, and average years. Over three consecutive years, the irrigation and N fertilizers rates were tested for their effect on grain yield and composition, i.e., protein, starch, and oil content of the maize hybrids; soil N level (%); and nitrate leaching. The results showed that the impact of the tested factors and their significance was year- or weather-condition-dependent. The grain yield result stood out during the extremely wet year, where the irrigation rate reduced the grain yield by 7.6% due to the stress caused by the excessive amount of water. In the remainder of the study, the irrigation rate expectedly increased the grain yield by 13.9% (a2) and 20.8% (a3) in the extremely dry year and 22.7% (a2) and 39.5% (a3) during the average year. Regardless of the weather conditions, the N fertilizer rate increased the grain yield and protein content. The soil N level showed a typical pattern, where the maximum levels were at the beginning of the study period and were higher as the N fertilizer rate was increased. Significant variations in the soil N level were found between weather conditions (r = −0.719) and N fertilizer rate (r = 0.401). Nitrate leaching losses were expectedly found for irrigation and N fertilizer treatments with the highest rates (a3b3 = 79.8 mg NO3− L).
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Claims 11
Claim · model-written summary
In the wet year, irrigation reduced grain yield by 7.6%.
- Treatment
- irrigation ratee0
- Outcome
- grain yielde0
- Direction
- reducede0
- Value
- 7.6%e0
- Qualifier
- extremely wet yeare0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“during the extremely wet year, where the irrigation rate reduced the grain yield by 7.6% due to the stress caused by the excessive amount of water”
t0“Maize”
Claim · model-written summary
In the dry year, irrigation rate a2 increased yield by 13.9%.
- Treatment
- irrigation ratee0
- Outcome
- grain yielde0
- Direction
- increasede0
- Value
- 13.9%e0
- Qualifier
- extremely dry yeare0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the irrigation rate expectedly increased the grain yield by 13.9% (a2) and 20.8% (a3) in the extremely dry year”
t0“Maize”
Claim · model-written summary
In the dry year, irrigation rate a3 increased yield by 20.8%.
- Treatment
- irrigation ratee0
- Outcome
- grain yielde0
- Direction
- increasede0
- Value
- 20.8%e0
- Qualifier
- extremely dry yeare0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the irrigation rate expectedly increased the grain yield by 13.9% (a2) and 20.8% (a3) in the extremely dry year”
t0“Maize”
Claim · model-written summary
In the average year, irrigation rate a2 increased yield by 22.7%.
Not reportedTreatmentComparatorOutcome
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“22.7% (a2) and 39.5% (a3) during the average year”
t0“Maize”
Claim · model-written summary
In the average year, irrigation rate a3 increased yield by 39.5%.
Not reportedTreatmentComparatorOutcome
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“22.7% (a2) and 39.5% (a3) during the average year”
t0“Maize”
Claim · model-written summary
Nitrogen fertilizer increased grain yield across weather conditions.
- Treatment
- N fertilizer ratee0
- Outcome
- grain yielde0
- Direction
- increasede0
- Qualifier
- Regardless of the weather conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regardless of the weather conditions, the N fertilizer rate increased the grain yield and protein content”
t0“Maize”
Claim · model-written summary
Nitrogen fertilizer increased grain protein content across weather conditions.
- Treatment
- N fertilizer ratee0
- Outcome
- protein contente0
- Direction
- increasede0
- Qualifier
- Regardless of the weather conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regardless of the weather conditions, the N fertilizer rate increased the grain yield and protein content”
t0“Maize”
Claim · model-written summary
Soil nitrogen was highest at the study beginning and rose with nitrogen fertilizer rate.
- Treatment
- N fertilizer ratee0
- Outcome
- soil N levele0
- Direction
- highere0
- Qualifier
- beginning of the study periode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The soil N level showed a typical pattern, where the maximum levels were at the beginning of the study period and were higher as the N fertilizer rate was increased”
t0“Maize”
Claim · model-written summary
Soil nitrogen varied significantly with weather conditions, with r = −0.719.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant variations in the soil N level were found between weather conditions (r = −0.719) and N fertilizer rate (r = 0.401)”
t0“Maize”
Claim · model-written summary
Soil nitrogen varied significantly with fertilizer rate, with r = 0.401.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant variations in the soil N level were found between weather conditions (r = −0.719) and N fertilizer rate (r = 0.401)”
t0“Maize”
Claim · model-written summary
The highest combined irrigation and nitrogen rates produced nitrate leaching of 79.8 mg NO3− L.
- Treatment
- irrigation and N fertilizer treatments with the highest ratese0
- Outcome
- Nitrate leaching lossese0
- Value
- 79.8 mg NO3− Le0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrate leaching losses were expectedly found for irrigation and N fertilizer treatments with the highest rates (a3b3 = 79.8 mg NO3− L)”
t0“Maize”
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