Citation: De Carvalho, A.M.; dos Santos, D.C.R.; Ramos, M.L.G.; Marchão, R.L.; Vilela, L.; De Sousa, T.R.; Malaquias, J.V.; de Araujo Gonçalves, A.D.M.; Coser, T.R.; De Oliveira, A.D. Nitrous Oxide Emissions from a Long-Term Integrated Crop–Livestock System with Two Levels of P and K Fertilization. Land 2022, 11, 1535. https://doi.org/10.3390/ land11091535 Academic Editors: Baojie He, Ayyoob Sharifi, Chi Feng and Jun Yang Received: 28 July 2022 Accepted: 8 September 2022 Published: 11 September 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). land Article Nitrous Oxide Emissions from a Long-Term Integrated Crop–Livestock System with Two Levels of P and K Fertilization Arminda Moreira De Carvalho 1, *, Divina Clea Resende dos Santos 2 , Maria Lucrecia Gerosa Ramos 2 , Robélio Leandro Marchão 1 , Lourival Vilela 1 , Thais Rodrigues De Sousa 2 , Juacy Vitória Malaquias 1 , Adriano Dicesar Martins de Araujo Gonçalves 1 , Thais Rodrigues Coser 2 and Alexsandra Duarte De Oliveira 1 1 Empresa Brasileira de Pesquisa Agropecuária, EMBRAPA Cerrados, Brasília 70910970, Brazil 2 Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília, Brasília 70910970, Brazil * Correspondence: arminda.carvalho@embrapa.br; Tel.: +55-61-996334908 Abstract: Nitrous oxide (N 2 O) emissions resulting from nitrogen (N) fertilization have been docu- mented. However, no data on the effects of other nutrients, such as phosphate (P) and potassium (K), on N 2 O emissions in integrated crop–livestock systems are available so far. In the 2015/2016 and 2016/2017 growing seasons, we measured N 2 O emissions from a long-term system, established in 1991 in the Cerrado biome (a tropical savanna ecoregion in Brazil), fertilized with two P and K levels. The studied no-tillage farming systems consisted of continuous crops fertilized with half of the recommended P and K rates (CC-F1), continuous crops at the recommended P and K rates (CC-F2), an integrated crop–livestock system with half of the recommended P and K rates (ICL-F1), and an integrated crop–livestock at the recommended P and K rates (ICL-F2). The cumulative N 2 O emissions (603 days) and soil chemical properties were analyzed as a 2 × 2 factorial design (long-term agricultural systems x fertilization). The cumulative N 2 O emissions from CC-F2 and ICL-F1 were 2.74 and 1.12 kg N ha −1 , respectively. The yield-scaled N 2 O emissions from soybean were 55.5% lower from ICL-F1 than from CC-F2 in the 2015/2016 growing season. For off-season sorghum, the mean yield-scaled N 2 O emissions were 216 mg N 2 Om −2 kg −1 (in a range from 79.83 to 363.52 mg N 2 Om −2 kg −1 , for ICL-F2 and CC-F1, respectively). The absence of pasture and the presence of soybean and sorghum promoted the highest cumulative N 2 O emissions, favored by the recommended rate in relation to half of the P and K. In the total evaluation period (603 days), the presence of grazed land in the years prior to this study and land fertilized with half the recommended P and K rates in an integrated crop–livestock system reduced the resulting cumulative N 2 O emis- sions by 59%. Thus, we conclude that crop–livestock systems can be beneficial in reducing P and K applications and also in mitigating N 2 O emissions in comparison with continuous cropping systems fertilized with the full recommended P and K rates. In view of the global fertilizer crisis, this aspect is extremely relevant for agriculture in Brazil and around the world. Keywords: sustainable agriculture; greenhouse gas emissions; low carbon agriculture 1. Introduction Brazil is one of the largest food producers in the world and accounts for 12% of the global agricultural production [1]. The Cerrado biome, with more than 2 million km 2 of savanna-like vegetation, is the most important agricultural region of the country. In the last four decades, nearly one million km 2 , or 50% of the total Cerrado area, has been converted into agricultural land [2]. The rapid agricultural expansion in the Cerrado has led to substantial changes in the biogeochemical cycles [3], particularly in the N and P dynamics, and increased greenhouse gases (GHG) emissions [4]. On a 100-year timescale of GHGs, the global warming potential (GWP) of nitrous oxide (N 2 O) is 6%, which is 265–298 times greater than that of carbon dioxide (CO 2 ), and its lifetime in the atmosphere is 121 years. [5,6]. The agriculture and livestock sector Land 2022, 11, 1535. https://doi.org/10.3390/land11091535 https://www.mdpi.com/journal/land