Soil net nitrogen mineralization and leaching under Miscanthus × giganteus and Zea mays

Abstract

The winter fallow period common in annual cropping systems leaves soils vulnerable to erosion and nutrient loss, especially to nitrogen (N) leaching. This vulnerability can be mitigated with perennial crops that have living roots in the ground year‐round. The mechanisms, magnitude, and consistency with which perennial crops retain N are not clear. We used an experiment to test whether a perennial crop, miscanthus (Miscanthus × giganteus Greef et Deu.), would leach less N than continuous maize (Zea mays L.) and how soil net N mineralization (Nmin) may explain observed leaching under varied environment and management conditions. The experiment included three crossed factors: (1) cropping system (maize, juvenile miscanthus = 1–2 years old, mature miscanthus = 3–4 years old); (2) N fertilization (0 and 224 kg N ha−1); and (3) environment (four site‐years at two locations in Iowa, USA, that differed in climate and soil fertility). We measured N cycling dynamics, including: inorganic soil N (ammonium + nitrate), in situ Nmin, N leaching, crop N uptake, and calculated system N use efficiency. There were many complex interactions among factors. On average, cumulative Nmin under juvenile miscanthus was 111% greater than maize, but as miscanthus matured, there was no difference in Nmin between the perennial crop and maize. There was no difference in N leaching between juvenile miscanthus and maize, but mature miscanthus decreased N leaching by 42% and 88% compared to maize (with and without N fertilization, respectively). Across all treatments, there was no relationship between Nmin and N leaching, suggesting other mechanisms are regulating N leaching. Overall, mature miscanthus shows promise as a tool to reduce N losses in areas dominated by annual row‐crops.

Response of Total (DNA) and Metabolically Active (RNA) Microbial Communities in Miscanthus × Giganteus Cultivated Soil to Different Nitrogen Fertilization Rates

“…Soils at the site are deep loams (>1m) formed over glacial till; the dominant soil type (53%) is a Webster clay loam (fine-loamy, mixed, superactive, mesic Typic Endoaquoll). Initially, at this site, soil conditions were considered nitrogen-limiting, with a relatively high C:N ratio (13.2) compared with the average of Northwest Iowa (10.8) ( 52 ). Fertilizer was applied as banded urea ammonium nitrate (UAN) in aqueous solution and side-dressed into the soil at 0.1 m depth on May 9, 2018, at rates of 0, 224, and 448 kg ha −1 N. Previous recommendations for nitrogen application for miscanthus range from 0 to 120 kg ha −1 N ( 30 , 73 , 74 ).…”

“…Fertilizer was applied as banded urea ammonium nitrate (UAN) in aqueous solution and side-dressed into the soil at 0.1 m depth on May 9, 2018, at rates of 0, 224, and 448 kg ha −1 N. Previous recommendations for nitrogen application for miscanthus range from 0 to 120 kg ha −1 N ( 30 , 73 , 74 ). The higher fertilization rates used in this study were selected based on the level of nitrogen-limitation in these soils and a parallel study occurring at this site which studied N leaching ( 52 ). The rationale for these higher nitrogen fertilization rates were both the level of nitrogen-limitation and parallel studies at this site focused on N leaching from these crops.…”

“…We hypothesize that microbiome responses (as indicated by DNA and RNA) to M. × giganteus management will differ and, specifically, that metabolically active (RNA) microbial communities will show a more rapid and sensitive response to fertilization than total (DNA) microbial communities. To test these hypotheses, soil samples were collected from the LAMPS site, a replicated chronosequence field previously used to investigate the effects of stand age and nitrogen fertilizer on M. × giganteus and corn ( Zea mays L.) ( 30 , 52 ). DNA and RNA were extracted from these soil samples, and we compared these microbial responses with stand age, N fertilization amount, and time since fertilization.…”

MetaFunPrimer: an Environment-Specific, High-Throughput Primer Design Tool for Improved Quantification of Target Genes

“…The soils are predominately Webster clay loams (Typic Endoaquolls), Canisteo clay loam (Typic Endoaquolls), and Clarion loam (Typic Hapludolls); this information was accessed from Web Soil Survey ( http://websoilsurvey.sc.egov.usda.gov/ ; accessed 22 July 2021). Surface soil (0 to 10 cm) is characterized as having a wide range in pH (5.3 to 7.8, 1:1 deionized [DI] water), above-average cation exchange capacity (32.2 ± 1.9 cmol kg −1 ), and soil organic matter (6.9% ± 2.8%) ( 43 ).…”

How to Reintroduce Arable Crops after Growing Perennial Wild Plant Species Such as Common Tansy (Tanacetum vulgare L.) for Biogas Production

“…Therefore, it is becoming increasingly important to use available resources as efficiently as possible within sustainable agriculture [3,4] and, in particular, rely on locally available resources and close nutrient circles as much as possible [5]. Here, perennial energy crops (PECs) can play an important role in bioeconomy, be it through their high tolerance to climate change-related cultivation limitations [6,7], their high nutrient use efficiency [8,9] or through their fulfillment of numerous ecosystem services, apart from the provision of biomass [10][11][12], which helps to substitute fossil energy sources. In addition to common PECs such as willow [13,14], Miscanthus [15,16], Sida [17,18], switchgrass [19,20] and cup plant [21,22], the cultivation of perennial wild plant mixtures (WPMs) is becoming increasingly important in Germany [23].…”