Nitrogen Losses: Gaseous and Leached Nitrogen Balance

Nitrogen is the element with the greatest influence on plant production and on protein content in the case of grain crops. Nevertheless, nitrogen over-fertilization produces environmental problems such as water pollution and global warming, which has led to the declaration of vulnerable zones to nitrate pollution in the European Union and to the adhesion of many countries to the Kyoto protocol. In the case of wheat there is a demand for producing quality grain, which is primed with a bonus price. Under these both economical and environmental circumstances, arose the need for a rational system of nitrogen fertilization which enabled the optimization of nitrogen use under the specific edaphoclimatic of Northern Spain. In order to cope with this objective a net of nitrogen fertilization assays was established by means of which a series of fertilization strategies together with some associated diagnosis tools were evaluated. Thus, N losses occurring both by nitrate leaching and by N2O emissions to the atmosphere were quantified, as well as plant N extractions regarding the different nitrogen fertilizer treatments applied

Biochar as a tool to reduce the agricultural greenhouse-gas burden–knowns, unknowns and future research needs

Agriculture and land use change has significantly increased atmospheric emissions of the non-CO2 green-house gases (GHG) nitrous oxide (N2O) and methane (CH4). Since human nutritional and bioenergy needs continue to increase, at a shrinking global land area for production, novel land management strategies are required that reduce the GHG footprint per unit of yield. Here we review the potential of biochar to reduce N2O and CH4 emissions from agricultural practices including potential mechanisms behind observed effects. Furthermore, we investigate alternative uses of biochar in agricultural land management that may significantly reduce the GHG-emissions-per-unit-of-product footprint, such as (i) pyrolysis of manures as hygienic alternative to direct soil application, (ii) using biochar as fertilizer carrier matrix for underfoot fertilization, biochar use (iii) as composting additive or (iv) as feed additive in animal husbandry or for manure treatment. We conclude that the largest future research needs lay in conducting life-cycle GHG assessments when using biochar as an on-farm management tool for nutrient-rich biomass waste streams. © 2017 The Author(s) Published by VGTU Press and Informa UK Limited, [trading as Taylor & Francis Group]

Biochar research activities and their relation to development and environmental quality. A meta-analysis

Biochar is the solid product that results from pyrolysis of organic materials. Its addition to highly weathered soils changes physico-chemical soil properties, improves soil functions and enhances crop yields. Highly weathered soils are typical of humid tropics where agricultural productivity is low and needs to be raised to reduce human hunger and poverty. However, impact of biochar research on scientists, politicians and end-users in poor tropical countries remains unknown; assessing needs and interests on biochar is essential to develop reliable knowledge transfer/translation mechanisms. The aim of this publication is to present results of a meta-analysis conducted to (1) survey global biochar research published between 2010 and 2014 to assess its relation to human development and environmental quality, and (2) deduce, based on the results of this analysis, priorities required to assess and promote the role of biochar in the development of adapted and sustainable agronomic methods. Our main findings reveal for the very first time that: (1) biochar research associated with less developed countries focused on biochar production technologies (26.5 ± 0.7%), then on biochars’ impact on chemical soil properties (18.7 ± 1.2%), and on plant productivity (17.1 ± 2.6%); (2) China dominated biochar research activities among the medium developed countries focusing on biochar production technologies (26.8 ± 0.5%) and on use of biochar as sorbent for organic and inorganic compounds (29.1 ± 0.4%); and (3) the majority of biochar research (69.0±2.9%) was associated with highly developed countries that are able to address a higher diversity of questions. Evidently, less developed countries are eager to improve soil fertility and agricultural productivity, which requires transfer and/or translation of biochar knowledge acquired in highly developed countries. Yet, improving local research capacities and encouraging synergies across scientific disciplines and countries are crucial to foster development of sustainable agronomy in less developed countries. © 2017, The Author(s)

Ammonium nutrition affects the accumulation of winter wheat glutenins

Trabajo presentado en el 17th International Nitrogen Workshop, celebrado en Wexford (Irlanda) del 27 al 29 de junio de 2012.Bread wheat quality is a highly complex feature which is mainly determined by the amount of grain protein and the qualitative composition of that protein. Nitrogen fertilization is the agronomic practice that most widely affects the quality, since the accumulation of reserve protein is influenced not only by the amount of N fertilizer, but also by the type and timing of N source applied. Nitrogen fertilization improves grain quality due to a rise in grain protein content (Fuertes- Mendizábal et al., 2011). However, the N source or splitting N application has a more variable effect on grain quality. The main objective of this study was to assess the effect of applying exclusively ammonium as the N source split into two or three applications during the crop lifecycle on the composition of the reserve protein fraction responsible for bread dough strength.Projects Etortek K-Egokitzen, RTA2009-00028-C03-03 and IT526-10.Peer Reviewe

Durum wheat quality traits affected by mycorrhizal inoculation, water availability and atmospheric CO2 concentration

Predicted reduced precipitation, enhanced evaporative demand and increasing CO in the atmosphere will strongly influence wheat production. The association of wheat with arbuscular mycorrhizal fungi (AMF) improves growth under stressful conditions. Our objective was to test the influence of mycorrhizal inoculation on yield, and accumulation of macro- and micro-nutrients and gliadins in grains of durum wheat (Triticum durum Desf.) plants grown under different CO concentrations and water regimes. The main factors of the experimental design were mycorrhizal inoculation (inoculated or non-inoculated plants); atmospheric CO concentration (ambient, ACO, or elevated, ECO); and water regime (optimal or restricted water regime). At ACO, the simultaneous application of AMF and water deficit decreased the number of seeds per spike without affecting the biomass of grains, and grains accumulated higher contents of copper, iron, manganese, zinc and gliadins. The opposite effect was observed with ECO where, regardless of mycorrhizal and water treatment factors, a general depletion of contents of micro- and macro-nutrients and gliadins was detected. Whereas mycorrhizal inoculation together with drought applied to plants cultivated at ACO improved wheat grain quality parameters, under ECO, mycorrhization did not ameliorate grain quality parameters detected in plants that produced the largest grain dry matter values.Peer Reviewe

High irradiance improves ammonium tolerance in wheat plants by increasing N assimilation

Ammonium is a paradoxical nutrient ion. Despite being a common intermediate in plant metabolism whose oxidation state eliminates the need for its reduction in the plant cell, as occurs with nitrate, it can also result in toxicity symptoms. Several authors have reported that carbon enrichment in the root zone enhances the synthesis of carbon skeletons and, accordingly, increases the capacity for ammonium assimilation. In this work, we examined the hypothesis that increasing the photosynthetic photon flux density is a way to increase plant ammonium tolerance. Wheat plants were grown in a hydroponic system with two different N sources (10mM nitrate or 10mM ammonium) and with two different light intensity conditions (300μmolphotonm-2s-1 and 700μmolphotonm-2s-1). The results show that, with respect to biomass yield, photosynthetic rate, shoot:root ratio and the root N isotopic signature, wheat behaves as a sensitive species to ammonium nutrition at the low light intensity, while at the high intensity, its tolerance is improved. This improvement is a consequence of a higher ammonium assimilation rate, as reflected by the higher amounts of amino acids and protein accumulated mainly in the roots, which was supported by higher tricarboxylic acid cycle activity. Glutamate dehydrogenase was a key root enzyme involved in the tolerance to ammonium, while glutamine synthetase activity was low and might not be enough for its assimilation. © 2013 Elsevier GmbH.This research was financially supported by the Basque Government (IT526-10, K-EGOKITZEN, ETORTEK 2010–12) and by the Spanish Government (MICINN-AGL 2009-13339-CO2-01, AGL 2012-37815-C05-02, RTA2009-00028-CO3-03). Technical support provided by M. Lema from the Unidade de Técnicas Instrumentais de Análise Servizos de Apoio á Investigación (Universidad de A Coruña) and by G. Garijo from the Departamento de Ciencias del Medio Natural (Universidad Pública de Navarra) are gratefully acknowledged. We are also grateful to Dr. K.A Roubelakis-Angelakis for lending GDH antibodies.Peer Reviewe

Assessing the evolution of wheat grain traits during the last 166 years using archived samples

The current study focuses on yield and nutritional quality changes of wheat grain over the last 166 years. It is based on wheat grain quality analyses carried out on samples collected between 1850 and 2016. Samples were obtained from the Broadbalk Continuous Wheat Experiment (UK) and from herbaria from 16 different countries around the world. Our study showed that, together with an increase in carbohydrate content, an impoverishment of mineral composition and protein content occurred. The imbalance in carbohydrate/protein content was specially marked after the 1960’s, coinciding with strong increases in ambient and temperature and the introduction of progressively shorter straw varieties. The implications of altered crop physiology are discussed.Tis work was supported by the Spanish Innovation and Universities Ministry (AGL2016-79868-R; PCIN2017-007), BBSRC Institute Strategic Programme grants, Designing Future Wheat (BB/P016855/1) and Soil to Nutrition (S2N, BBS/E/C/00I0310), the Long-term Experiments National Capability grant (BBS/E/C/000J0300), the Lawes Agricultural Trust and the Basque Country Government consolidated group programme (IT‐932‐16).Postprint (published version