Soil Respiration Under 90 Year-Old Rye Monoculture and Crop Rotation in the Climate Conditions of Central Poland
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agronomy Article Soil Respiration under 90 Year-Old Rye Monoculture and Crop Rotation in the Climate Conditions of Central Poland Tomasz Sosulski 1 , Magdalena Szyma ´nska 1,* , Ewa Szara 1 and Piotr Sulewski 2 1 Department of Agricultural Chemistry, Institute of Agriculture, Warsaw University of Life Sciences, Nowoursynowska 159, 02-766 Warsaw, Poland; [email protected] (T.S.); [email protected] (E.S.) 2 Institute of Economics and Finances, Warsaw University of Life Sciences, Nowoursynowska 166, 02-787 Warsaw, Poland; [email protected] * Correspondence: [email protected]; Tel.: +482-2593-2625 Abstract: This study, aimed at assessing the rate of soil respiration under different crop rotation and fertilization conditions, was carried out on long-term (since 1923) experimental plots with rye monoculture and 5-crop rotation in Skierniewice (Central Poland). The treatments included mineral- organic (CaNPK+M) and organic (Ca+M) fertilization (where M is farmyard manure). Soil respiration was measured in situ by means of infrared spectroscopy using a portable FTIR spectrometer Alpha. CO2 fluxes from CaNPK+M-treated soils under cereals cultivated in monoculture and crop rotations were not statically different. Respiration of soil under lupine cultivated in crop rotation was higher than under cereals. N-fertilization and its succeeding effect increased soil respiration, and significantly altered its distribution over the growing season. Our results indicate that in the climatic conditions of Central Europe, respiration of sandy soils is more dependent on the crop species and fertilization than on the crop rotation system. Omission of mineral fertilization significantly decreases soil respiration. The CO2 fluxes were positively correlated with soil temperature, air temperature, and soil content of NO − and NH +. 3 4 Citation: Sosulski, T.; Szyma´nska,M.; Keywords: long-term experiment; GHG emissions; monoculture and crop rotation; legumes; fertilization Szara, E.; Sulewski, P. Soil Respira- tion under 90 Year-Old Rye Monocul- ture and Crop Rotation in the Climate Conditions of Central Poland. 1. Introduction Agronomy 2021, 11, 21. Arable land plays a fundamental role in global carbon cyclical exchange between https://dx.doi.org/10.3390/ the lithosphere and atmosphere [1,2]. Cultivated soils are considered both a source and agronomy11010021 sink of atmospheric CO2 [3,4]. According to Ding et al. [5] and Paustian et al. [6], 25–29% Received: 1 November 2020 of anthropogenic CO2 input to the atmosphere can be assumed to come from cultivated soils. Accepted: 23 December 2020 Therefore, arable land is considered an important source of CO2 loss to the atmosphere [7]. Published: 24 December 2020 The key factors affecting soil respiration include content of soil organic carbon, fertilization, temperature and soil moisture, and soil tillage intensity [8–11]. Numerous scientific papers Publisher’s Note: MDPI stays neu- have shown that the most important drivers of soil respiration are both air/soil temperature tral with regard to jurisdictional claims and soil moisture [12,13]. Buragiene˙ et al. [14] and Bogužas et al. [15], however, found a in published maps and institutional negative correlation between soil CO2 fluxes and temperature. Negative influence of soil affiliations. moisture on soil respiration has also been described in literature [16,17]. Higher content of soil organic carbon contributes to a higher rate of CO2 soil respiration [12]. Different cropping systems and mineral/organic fertilization can significantly alter the content of organic carbon in the soil [18]. An increase in soil organic carbon observed in mineral Copyright: © 2020 by the authors. Li- treated soil was lower than that observed by manure fertilization [18,19]. Sosulski and censee MDPI, Basel, Switzerland. This Korc [19] found that mineral fertilizers (no application of organic amendments) led to an article is an open access article distributed increase in organic carbon content in soil. Although mineral NPK fertilizers were applied, under the terms and conditions of the Creative Commons Attribution (CC BY) nitrogen was the main contributor to increase inorganic carbon content in the soil. Higher license (https://creativecommons.org/ organic carbon content in the mineral fertilized soils resulted from greater input of crop licenses/by/4.0/). residues in comparison to non-treated soils [20]. In addition to promoting higher crop Agronomy 2021, 11, 21. https://dx.doi.org/10.3390/agronomy11010021 https://www.mdpi.com/journal/agronomy Agronomy 2021, 11, 21 2 of 16 biomass production, mineral fertilization, in particularly nitrogen, intensifies the microbial processes responsible for soil organic matter decomposition. Sainju et al. [10] and Song and Zhang [13] observed that soil respiration from N-fertilized soils was higher by 14% than that from non-fertilized soils. The effect of nitrogen fertilization on soil respiration is not always observed. For example, Zhang et al. [21] found a 4% increase in root respiration after NPK fertilization, while Alluvione et al. [16] and Zhai et al. [22] reported that N-fertilization did not affect soil respiration. Moreover, Ding et al. [23] reported that N-fertilization decreased CO2 soil fluxes by 10.5%. The negative influence of applying high nitrogen fertilizer rates on soil respiration was also reported by Song and Zhang [13]. Pareja-Sánchez et al. [24] found that the effect of nitrogen fertilization could be different depending on the tillage conditions. Grant at al. [25] reported that it may be difficult to determine the influence of N-fertilization on CO2 soil emissions. For example, the authors found only a slight increase in CO2 soil fluxes after increasing and decreasing the rate of nitrogen fertilizer by 50%. However, the influence of soil manuring on soil respiration tends to be more pronounced. An increase in soil respiration after solid and liquid manure application has been observed in several studies [21,22,26,27]. The effect of soil tillage is broadly discussed in international scientific literature [7,10,24,28]. Nonetheless, literature reports have provided divergent opinions on the effect of different cropping systems on soil respiration. For example, Omonode et al. [29] found higher CO2 soil fluxes under continuous corn than under corn cultivated in rotation. Campbell et al. [30] also reported that soil respiration under corn after corn cultivation was higher in comparison to corn after soybean cultivation. Shen et al. [31] reported that maize monoculture had greater direct greenhouse gas emission (GHG) than the maize soybean intercrop treatment, although it was the largest C sink due to its higher net primary production. On the other hand, Norberg et al. [32] stated that soil respiration was not affected by crop rotation. However, Herridge and Brock [33] found that CO2 fluxes under canola were higher than those from soil under pea. This suggest that soil respiration for different plant species can vary. Discrepancies in the results of international research on soil respiration from different cultivated and fertilized soils in varied climatic and soil conditions limit the ability to distinguish between the effects of cropping systems (including monoculture and crop rotation) and the effects of fertilization of sandy soils occurring in Central and Eastern Europe. These soils are usually characterized by low content of organic matter, and lower yielding potential affected by the soil water regime and low nutrients content [18]. An improvement of soil properties is usually obtained through mineral-organic fertilization, remaining a typical practice in Polish agricultural conditions. In order to provide an insight into the effects of crop rotation and fertilization on soil respiration, we conducted a study on a 90 year-old long-term field (since 1923) experiment located in Skierniewice (Central Poland) to quantify soil respiration under a rye monoculture and 5-crop rotation system. The objective was to determine the effect of environmental factors, different crop rotations and cultivation of legumes, and mineral fertilization on soil respiration. 2. Materials and Methods 2.1. Experiments The research was carried out in 2012 and 2013 on two long-term field experiments in Skierniewice (51◦9606000 N, 20◦1606300 E, Central Poland) belonging to the Warsaw University of Life Sciences—SGGW, maintained with no alterations since 1923. The soil is Luvisols (FAO 2006) of the type of loamy sand with the following fractions in the 0–25 cm layer (Ap horizon): 7% < 0.002 mm; 5% 0.002 to 0.05 mm; 87% > 0.05 mm, in the 26–45 cm layer (Eet horizon): 5% < 0.002 mm; 5% 0.002 to 0.05 mm; 90% > 0.05 mm, below 45 cm of depth (Bt/C horizon) 14% < 0.002 mm; 8% 0.002 to 0.05 mm; 78% > 0.05 mm. Plants were cultivated using two different cropping systems: − Experiment E—5-field crop rotation: potatoes, spring barley, yellow lupine, winter wheat, rye—in the years of the study, spring barley (2012) and yellow lupine (2013) were cultivated, Agronomy 2021, 11, 21 3 of 16 − Experiment D—rye monoculture. Both experiments were conducted in a randomized block design in 5 replications with an experimental plot area of 36 m2. The investigation was conducted on Experiment D (mineral fertilizers and manure, CaNPK+M) and Experiment E (mineral fertilizers and manure, CaNPK+M and solely with manure, Ca+M). Manure was applied at a rate of 30 t ha−1 in 4-year intervals on CaNPK+M treatment of the experiment with rye monocul- ture, and at the same rate every 5 years (potatoes) on both Ca+M and CaNPK+M treatments in Experiment E. On both experiments, the investigations were conducted in the 2nd and 3rd year after soil manuring. On the mineral fertilized treatments (CaNPK+M) of both Experiments (D and E), mineral fertilizers were applied at the following rates: 90 kg N (ammonium nitrate), 26 kg P (triple superphosphate), and 91 kg K ha−1 (potassium chloride 50%). Lupine cultivated in Experiment E was not treated with nitrogen fertilizers.