Effects of different rates and timing of application of nitrogen as slurry and mineral fertilizer on yield of herbage and nitrate‐leaching potential of a maize/Italian ryegrass cropping system in north‐west Portugal

Abstract

Efficient use of cattle-slurry to avoid nitrogen (N) leaching and other losses is important in designing intensive dairy systems to minimize pollution of air and water. The response in dry-matter (DM) yield of herbage and nitrate-leaching potential to different rates and timing of application of N as cattle slurry and ⁄ or mineral fertilizer in a double-cropping system producing maize (Zea mays L.) silage and Italian ryegrass (Lolium multiflorum Lam.) was investigated in north-west Portugal. Nine treatments with different rates and combinations of cattle slurry, and with or without mineral-N fertilizer, applied at sowing and as a top-dressing to both crops, were tested and measurements were made of DM yield of herbage, N concentration of herbage, uptake of N by herbage and amounts of residual soil nitrate-N to a depth of 1 m, in a 3-year experiment. Regression analysis showed that the application of 150 and 100 kg of available N ha )1 to maize and Italian ryegrass, respectively, resulted in 0AE95 of maximum DM yields of herbage and 0AE90 of maximum N uptake by herbage. Residual amounts of nitrate-N in soil after maize ranged from 48 to 278 kg N ha )1 with an exponential increase in response to the amount of N applied; there were higher values of nitrate-leaching potential when mineral-N fertilizer was applied. The results suggest that it is possible in highly productive maize ⁄ Italian ryegrass systems to obtain high DM yields of herbage for maize silage and Italian ryegrass herbage with minimal leaching losses by using slurry exclusively at annual rates of up to 250 kg available N ha )1 (equivalent to 480 kg total N ha )1 ) in three applications.

Options to reduce N loss from maize in intensive cropping systems in Northern Italy

“…The double-cropping system yield and N uptake in this study was not as high as that reported in other Italian (Onofrii et al, 1993) and Portuguese (Trindade et al, 2008) studies; in those instances, maize produced 10-20% more biomass. The yields and uptakes of grass leys were also similar to those obtained in local farm…”

Assessing Nitrogen Use Efficiency and Nitrogen Loss in a Forage-Based System Using a Modeling Approach

“…NO 3´p ollution is a relevant issue for intensive livestock farms where liquid and solid manure as organic effluents are used [22][23][24][25]. NO 3´l eaching is particularly serious in Mediterranean semi-arid countries [23,26], where substantial N losses by leaching were found to occur during the rainy period in winter and after irrigation practice in summer. To date, the relationships between soil NO 3´a ccumulation and groundwater NO 3ć oncentrations in agricultural soils are still not entirely understood [1].…”

The efficiency of nitrogen in cattle manures when applied to a double‐annual forage cropping system

“…These results are similar to those obtained by Trindade et al . () in a double‐cropping system when producing maize and ryegrass, in north‐western Portugal, in which it was necessary to apply more than 400 kg N ha −1 year −1 from organic materials in order to obtain high yields. In addition, it is not unusual in the study area to find that the first organic applications, after years without them, can cause soil mineral N immobilization (Domingo Olivé et al ., , ) to balance the C/N ratio of the organic matter applied and that from the soil.…”

“…Trindade et al . (), in a rotation of maize (silage) with Italian ryegrass (forage), determined an annual rate of up to 250 kg available N ha −1 from slurry as the requirement to obtain high productivity while also minimizing leaching losses. Nevertheless, in humid Mediterranean environments, data on N efficiency and NFRV of manures are still lacking for situations when a double‐annual cropping rotation is implemented and the crops are harvested as fodder.…”