Long‐Term Effects of Mineral Nitrogen Fertilizer on Irrigated Maize and Soil Properties

Abstract

Core Ideas Grain yield, biomass, N uptake, SPAD units, soil N levels and N efficiciencies were affected by the N application rate. Maximum grain yields required 203 kg N ha−1 of available N in the 0‐ to 30‐cm layer soil. Sampling to a depth of 0 to 30 cm provided similar correlations than sampling to 0 to 60 and 0 to 90 cm. Mineral N fertilization increased soil organic C stock. Nitrogen is a key determinant of growth and grain yield (GY) in maize (Zea mays L.) and is therefore economically and environmentally important. We investigated the performance of maize crops in a 12‐yr experiment (2002–2007, 2010–2015) under sprinkler irrigation in a petrocalcic calcixerept soil in northeastern Spain, with controlled mineral N application rates (0, 100, 150, 200, 250, 300, and 400 kg N ha−1 yr−1). The application rate affected maize GY, biomass, N uptake, SPAD units, soil N levels, N efficiencies, and soil organic carbon (SOC). Average maximum GY's (∼15 Mg ha−1) required 203 kg N ha−1 of available N (defined as initial soil NO3− plus N fertilizer) in the 0‐ to 30‐cm horizon, confirming the importance of the soil N content. Nitrate levels in the 0‐ to 30‐cm horizon for maximum yields achieved a R2 value in the plateau fitting model similar to the 0‐ to 60‐ and 0‐ to 90‐cm horizons. The GY's increased at a rate of 192 kg ha−1 yr−1, suggesting a combination of genetic improvement in the hybrids and also an improvement in agronomic management. The 200 kg N ha−1 fertilizer treatment achieved almost the highest GY's (∼14 Mg ha−1) with simultaneous high nitrogen use efficiency (NUE) (0.83 kg kg−1). Mineral N fertilization also increased the stock of SOC in the 0‐ to 30‐cm horizon.

Impact of tillage and N fertilization rate on soil N2O emissions in irrigated maize in a Mediterranean agroecosystem

“…Different studies have focused on N fertilization strategies in irrigated maize under Mediterranean conditions (e.g. Martínez et al, 2017;Berenguer et al, 2009). However, to our knowledge none of them have tested the performance of conservation tillage and its interaction with N fertilization on irrigated maize productivity.…”

Sowing Date Affects Maize Development and Yield in Irrigated Mediterranean Environments

“…Optimum SD vary from one environment to another [8]. In the Ebro valley, the month of April is the most recommended sowing period for maize, particularly, the first half of the month [20][21][22]. Even so, there can be year-to-year variations associated with temperatures and rainfall during spring.…”

Is it feasible to reduce tillage and N use while improving maize yield in irrigated Mediterranean agroecosystems?

“…In this line, Al-Kaisi and Yin (2003) suggested that the traditional application rate used by farmers in north eastern Colorado in maize production (250 kg N ha -1 ) could be reduced to 140 kg N ha -1 without losses in grain yield, since high N rates led to a decrease in nitrogen use efficiency as soil water content decreased. Similarly, in a maize experiment in the NE Spain comparing different mineral N application rates, Martínez et al, (2017) reported that the lowest N fertilization rate sufficient to achieve optimal yields was 200 kg N ha -1 . In our experiment, in all the three years studied, the NUE and the NAR decreased when increasing the rate of N from 200 to 400 kg N ha -1 , obtaining an improvement of 47% in NAR when 200 kg N ha -1 were applied compared with 400 kg N ha -1 .…”

“…Therefore, the most effective means to ensure high yields while reducing N loss and thus environmental damage is to improve the nitrogen use efficiency (NUE) of crops (Davidson et al, 2015). In a long-term irrigated experiment with maize managed under CT and comparing different mineral N rates (0,100,150,200,250,300 and 400 kg N ha -1 ) also in the Ebro valley, Martínez et al (2017) observed the highest NUE and grain yield when applying 200 kg N ha -1 . Therefore, in the study area, it is feasible the reduction in maize N fertilization while maximizing maize yields.…”