Nitrogen return in an integrated crop-livestock system with irrigation and forage legumeAbstract
Expanding the use of different practices in integrated crop livestock system (ICLS) is essential to understanding the dynamics of nitrogen (N) return. This study evaluated the influence of legume and irrigation on nitrogen return in ICLS. The four treatments were: irrigated and non-irrigated x intercropped and not intercropped with legume, in a 2x2 factorial scheme in randomized blocks experimental design with three replications. The ICLS area was cultivated, in winter, with pasture of black oat (Avena strigosa) and ryegrass (Lolium multiflorium) overseeded in african star (Cynodon sp.), and vetch (Vicia sativa) in the intercropped paddocks, with rotational grazing method. And, in summer, with corn (Zea mays). Data were subjected to analysis of variance (F test, p<0.05). There were no significant effects of irrigation and legumes on the return of N through feces, urine, and pasture residues. Grain yield, straw, extraction, export, and return of N by corn were similar among treatments. The average total N return was 335.61 kg ha-1. Irrigation and intercropping with legumes did not influence N return in ICLS, after one-year evaluation.
Key-words:
sustainable agriculture; nutrient balance; mixed cropping; grain yield.
Resumo
Ampliar o uso de diferentes práticas em Sistemas Integrados de Produção Agropecuária (SIPA) é essencial para compreender a dinâmica do retorno de nitrogênio (N). Este estudo avaliou a influência da leguminosa e da irrigação no retorno de N em SIPA. Os quatro tratamentos foram arranjados em esquema fatorial 2x2 (irrigação x consorciação), sendo eles, irrigado e não irrigado, consorciado com leguminosa e não consorciado, dispostos em delineamento de blocos ao acaso com três repetições. A área experimental foi cultivada no inverno com pastagem de aveia preta (Avena strigosa) mais azevém (Lolium multiflorium), e a ervilhaca (Vicia sativa), implantada nos tratamentos consorciados, com pastejo rotacionado. No verão, o milho (Zea mays) foi cultivado em toda área. Os dados foram submetidos à análise de variância (Teste F, p>0,05). Não se observaram efeitos significativos da irrigação e da leguminosa no retorno de N pelas fezes, pela urina e pelos resíduos da pastagem. A produção de grãos, a palhada, a extração, a exportação e o retorno de N pelo milho foram semelhantes entre os tratamentos. O retorno médio total de N foi de 335,61 kg ha-1. Após um ano de avaliação, a irrigação e o consórcio com leguminosa não influenciaram no retorno de N em SIPA.
Palavras-chave:
agricultura sustentável; balanço de nutrientes; cultivo misto; rendimento de grãos.
1. Introduction
The increasing adoption of integrated crop-livestock systems (ICLS) presents a sustainable alternative for intensifying agricultural production amid current global demands for food and environmental conservation in the context of climate change (1,2). Within ICLS, nutrient cycling, which is facilitated by the integration of animals with crops in rotational systems, can enhance the utilization of natural resources across the soil-plant-animal-atmosphere continuum (3), thereby increasing the profitability of these systems (4). The processes of chewing and digestion by grazing animals act as catalysts for nutrient turnover, accelerating nutrient cycling. Nutrients are returned to the soil through urinary and fecal excretions in forms available for uptake by plant root systems (5).
The use of legumes in ICLS-managed pastures is a technology that can reduce reliance on external inputs and promote higher biomass production, thereby increasing the sustainability of production systems (6). Incorporating legumes into pastures yields benefits such as biological nitrogen (N2) fixation (2), enhanced ecosystem diversity, and improvements in animal nutrition through increased crude protein content.
In addition, implementing irrigation systems is an important strategy for balancing forage availability and quality. Irrigation contributes to increased productivity, greater leaf production, and elevated levels of crude protein and forage digestibility (7). Regarding subsequent crops, specifically maize, Sah et al. (8) noted that although adequate water up to the vegetative stage is beneficial, the most critical period for yield occurs from the pre-flowering to grain-filling stages, during which maize yield is particularly sensitive to water availability.
In this context, the combined or individual use of forage legumes and irrigation in winter pastures and summer crops can significantly affect nutrient return and balance, as well as animal and crop production in succession. Specifically, these practices enhance biological N fixation by legumes and improve the effects of water supplementation during periods of water deficit, resulting in greater overall system biomass production.
Therefore, this study aimed to evaluate whether N return through system residues and maize yield are influenced by the application of irrigation and the intercropping of grasses and legumes in an integrated crop-livestock system.
2. Material and methods
The experiment was conducted at the Federal Technological University of Paraná (UTFPR) in Dois Vizinhos, Paraná State, Brazil (25°44” S, 54°04” W, 520 m altitude). The local soil is classified as Dystroferric Red Nitosol (Nitossolo Vermelho distroférrico) (9), and the climate is characterized as humid subtropical mesothermal (Cfa) (10), with an annual rainfall of 1800-2000 mm. For more than four years, the experimental area has been cultivated with Bermuda grass (Cynodon sp.) during the summer, and overseeded with black oats (Avena strigosa) and ryegrass (Lolium multiflorum) in the winter under beef cattle grazing.
During the winter and spring of 2016, the area was subdivided into 12 experimental units, each measuring 0.072 ha. Treatments consisted of two factors: irrigation (applied or not applied) and intercropping with legumes (performed or not performed) in the winter pasture. The experimental design was a randomized block in a 2 × 2 factorial arrangement with three replications. In winter, the pasture consisted of black oat and ryegrass, with and without intercropping with vetch (Vicia sativa), and with and without irrigation; maize (Zea mays L.) was grown in the summer. The soil chemical characteristics are presented in Table 1.
The sprinkler irrigation system consisted of 60 NY 25 sprisnklers, with a flow rate of 597 L ha-1 and an application rate of 2.2 mm h-1, positioned at a height of 2 m, 18 m apart between rows, and 15 m apart between sprinklers. The system was activated when the soil water potential reached a value of 10 kPa or greater, as measured by tensiometers installed in the area. Air temperature and rainfall were monitored at the UTFPR weather station (Figure 1).
Accumulated rainfall and average air temperature from April 2016 to March 2017 in the experimental area. Dois Vizinhos, Paraná.
The pasture was established at the end of April 2016 by sowing ‘BRS 139’ black oat using no-tillage, with a seed density of 60 kg ha-1 and 0.17 m row spacing. ‘Fepagro São Gabriel’ ryegrass was sown in the field at a rate of 55 kg ha-1. In intercropped paddocks, ‘Ametista’ vetch was sown in the same manner as oats, using 30 kg ha-1, with rows perpendicular to those of the oats. Base fertilization consisted of 300 kg ha-1 of N-P-K (5-20-20), and urea (45% N) was applied as a top dressing at a total rate of 150 kg ha-1 of N, divided into five applications.
Grazing was managed through rotational grazing, with a pre-grazing height of 0.30 m, measured using a ruler at five points in each paddock. Two steers were allocated to each experimental unit (0.072 ha), totaling 24 animals distributed among the treatments. Animal removal was determined by the pre-grazing height in the subsequent paddock, with a minimum residual height of 0.10 m. If the subsequent paddock did not reach the required entry height while the current paddock did, animals were removed, weighed, and kept in a similar area until re-entry was feasible. This period was accounted for in the calculation of the stocking rate.
Twenty-four Angus and Charolais steers, with an initial mean weight of 162 ± 11.3 kg and aged 6-10 months, were used. The animals underwent an 18-day adaptation period in the paddocks, where they remained throughout the winter and spring, totaling 130 days of grazing. At the end of the grazing period, pasture residues were desiccated with glyphosate herbicide (3 L ha-1). The study was approved by the Institutional Animal Care and Use Committee of UTFPR (protocol no. 2016-015).
Maize was sown in mid-November using a no-till system with a seeding rate of 3.6 seeds per linear meter of the "Pioneer 30F53VYH" hybrid and a row spacing of 0.45 m. The basal fertilizer applied was 439 kg ha-1 of N-P-K (8-20-10), and a topdressing of 90 kg ha-1 of N (urea, 45% N) was performed at the V6 stage. Pest control at the V4 stage employed the pyrethroid lambda-cyhalothrin and the anthranilamide chlorantraniliprole (150 mL ha-1) to control the fall armyworm (Spodoptera frugiperda).
For pasture evaluations, the rate of dry matter accumulation at pre-grazing (entry) and post-grazing (exit) was determined by harvesting the entire pasture within a 0.25 m2 quadrat at four locations. Samples were weighed and divided, with one portion used for determining the botanical composition, dead material (%), and vetch (%), and the other portion dried (55 °C for 72 h) to assess dry matter content. Forage mass was calculated before and after grazing. Based on these measurements and the number of days between grazing cycles, the daily accumulation rate and total dry matter production were calculated. On the second day after the animals entered the paddock, pasture samples were collected through simulated grazing (11). These samples were dried and ground (Willey mill, 1 mm) for in vitro digestibility determination and to determine the N content of the ingested pasture and dead material, which was then analyzed for N content (12,13).
The animals were weighed every 28 days after a 12-hour fast to determine live weight (LW) and stocking rate. For intake and excreta assessments, four steers from the same genetic group were housed in each module for a 7-day adaptation period and a 12-day evaluation period, as per a 4 × 4 Latin square design (4 treatments × 4 periods). Each animal received 10 g of titanium dioxide daily at 10:00 am via esophageal probe. From days 8 to 12, fecal samples were collected rectally twice daily (10:00 am and 4:30 pm), then stored at -10 °C. Fecal samples were dried (forced ventilation at 55 °C for 72 h) and ground (Willey mill, 1 mm) for determination of titanium concentration, fecal output, and daily dry matter intake(14).
Urine samples were collected daily at 10:00 am from days 8 to 12 as spot samples. A 10-mL aliquot was acidified with 40 mL of sulfuric acid (0.036 N) for total N determination, and a separate 50-mL aliquot was retained for creatinine analysis using a commercial kit (LABTEST Diagnostica, Brazil) to estimate daily urine output (15). Composite urine and fecal samples were analyzed for N content (13).
To evaluate the nutritional status of maize, one week after flowering began, the first leaf below the main ear was collected from 20 consecutive plants in three rows. Grain yield was determined by harvesting ears from two 4-m rows at four locations. All harvested ears were mechanically threshed, and the grains were weighed to determine moisture content and yield, with moisture standardized to 13 %. For crop residue analysis, plants (without grain) from two 1-m rows were collected and weighed. Subsamples of maize leaves, grains, and plant residues were dried (forced ventilation at 55 °C for 72 h), ground (Willey mill, 1 mm), and analyzed for N content (13).
For the statistical analysis, data were subjected to analysis of variance using the F-test, with a significance level of 5 % (p < 0.05). If the interaction between factors was not significant, main effects were evaluated independently of each other. In cases of significant interaction, means were compared using the t-test (p < 0.05), as Tukey’s test was not applicable in certain situations due to data structure. Analyses were performed using the SAS software.
3. Results and discussion
The mean LW, stocking rate, total dry matter production, and pasture residue at the end of the cycle did not differ significantly among the evaluated factors (Table 2). Although previous studies suggest that irrigation increases dry matter production (7), in our study, the regular distribution of rainfall (132 mm/ month) was sufficient to meet the plants’ water requirements, resulting in limited use of the irrigation system (Figure 1). Consequently, irrigation had no significant impact on either dry matter production or animal stocking rates. The N concentration in the grazing simulation samples and the pasture residue before crop implementation was similar (Table 2). When necessary, irrigation can increase the N content in pastures, leading to a grazed mass with a higher crude protein concentration due to greater differentiation in pasture structure and increased leaf production (7).
Production parameters, nitrogen concentration, and animal consumption during winter/spring (130 days) in an integrated crop-livestock system using irrigation and pasture intercropped with legumes.
Similarly, pastures intercropped with legumes generally present a higher N content, which may be attributed to increased absorption resulting from biological N2 fixation via symbiosis with bacteria of the Rhizobium genus, thereby raising the crude protein content (16). However, this effect was not observed in our study, likely due to the low proportion of vetch in the forage canopy (2-5 %), which may be attributed to competition between this species and grasses (oats and ryegrass) (17).
Dry matter intake was similar across treatments, ranging from 3.2 to 3.4 % of LW (Table 2). Daily N intake also did not differ between treatments (Table 2). Similarly, due to the absence of differences in stocking rate, both daily and total N consumption per area were comparable among treatments (Table 2). On average, 282.70 kg ha-1 of N were mobilized by the animals during the evaluation period, thereby increasing the cycling of this element within the system. Since only 5-20 % of ingested N is retained by the animal, the remainder is excreted in feces and urine (18,19).
The daily production of feces and urine was not significantly affected by irrigation or by intercropping with vetch, and N concentrations in urine and feces also did not differ among treatments (Table 3). On average, the N content in feces was 27.25 g kg-1 DM, which is consistent with the 27-32 g kg-1 DM reported by Garcia et al. (20). In urine, the average N concentration was 7.60 g L-1, similar to the 7.2 g L-1 reported by Selbie et al. (21) as being typical for beef cattle urine.
Nitrogen production and concentration in animal excreta during winter/spring (130 days) in an integrated crop-livestock system using irrigation and pasture intercropped with legumes.
In addition, the daily return of N from feces and urine was similar between treatments (Table 3), which can be attributed to the absence of differences in the crude protein content of the forage consumed. Nitrogen excretion in urine and feces is dependent on the crude protein concentration in the feed (22). The total return of N via animal excretion averaged 158.18 kg ha-1, with 76 % excreted through urine and 24 % through feces. These results corroborate the findings of Lessa et al. (23), who reported that most of the N excreted by cattle is returned to the soil via urine.
In urine, 60-90 % of N is present as urea, which is converted to ammonia in the soil by urease, increasing the susceptibility of N to losses (24). The extent of these losses depends on various factors, including temperature, vegetation cover, humidity, and soil texture. In pastures, urinary N can be lost primarily through volatilization, as well as through surface runoff, while denitrification results in losses as N2 and N2O (25).
The total N return per hectare was lower in both treatments without irrigation and legumes, as well as in the treatment with irrigation and legumes (Table 3). Although the initial hypothesis anticipated a greater N return in the legume-intercropped treatment, the proportion of legumes in the pasture was low (5-10 %), likely due to competition with grasses, natural selection, and other uncontrollable factors (26). A comparable situation was observed with irrigation, whose effectiveness was mitigated by evenly distributed rainfall throughout the experimental period (Figure 1), which may have offset the expected effects of irrigation and legume intercropping. During the cultivation of summer maize, N concentrations in the flag leaf did not differ among treatments (Table 4). According to the Brazilian Society of Soil Science (27), leaf N levels of 2.7-3.5 % are considered adequate for maize development. No differences were observed in the N content of grains and straw (Table 4). Grain yield remained, on average, at 9497 kg ha-1, and straw yield averaged 10,976 kg ha-1; the irrigation and legume intercropping treatments influenced either one during winter (Table 4). As in the winter and spring periods, the average monthly rainfall of 162 mm, distributed evenly (Figure 1), was sufficient to meet the plants’ water requirements. The similarity in grain yield between the grass-legume consortia may be attributed to the low presence of legumes in the pasture, which did not result in a substantial increase in residual N.
Maize parameters in an integrated crop-livestock system using irrigation and pasture intercropped with legumes.
The total N return via pasture residue prior to the cultivation phase was similar among the treatments (Figure 2B), as there were no significant differences in either the amount or content of N in the residue, with an average of 79.56 kg ha-1 of N. However, the return of urinary N per hectare exhibited a significant interaction (Figure 2B), with lower values observed in the treatments with legume irrigation and those without legumes under non-irrigated conditions. Although the daily N return through urine per unit of LW did not show a significant interaction (Table 3), this difference may be attributed to the stocking rate, which directly influences the N return per area. Thus, despite similar proportional excretion across treatments, the total amount of N excreted per hectare differed. Since urinary N represents, on average, 76% of the total N excreted, this difference was also reflected in the total N return (urine + feces), which explains the lower values observed in these two treatments.
(A) Total nitrogen return and (B) amount of nitrogen measured in an integrated crop-livestock system using irrigation and pasture intercropped with legumes.
On average, the total N return in winter/spring was 237.7 kg ha-1, of which 67% corresponded to N returned via feces and urine, and 33% to N derived from pasture residue.
Considering agricultural practices, the mean N export was 94.69 kg ha-1 in grain (p = 0.3490) and 97.87 kg ha-1 in straw (p = 0.4115), with no significant differences among the evaluated factors and treatments. The relationship with grain yield and straw dry matter resulted in means of 9.95 and 8.97 kg ton-1 N in straw and grain, respectively. The combined export in grain and return in straw amounted to 195.18 kg ha-1 N, with no differences observed between treatments. The total N returned to the system was approximately 336 kg ha-1, comprised primarily of N from maize residues (29%), pasture residues (24%), urinary N (36%), and fecal N (11%) (Figure 2). Of the total N returned, 71% occurred during the winter/spring period, with the majority derived from animal excreta.
Although the total N return per hectare showed a significant interaction between irrigation and legume intercropping, with lower values observed in the irrigated and non-irrigated legume treatments, it is important to note that these practices, when well established, can still contribute to the sustainability of the system. Irrigation can improve nutrient distribution and uptake by roots, as well as reduce losses through volatilization, particularly under water deficit conditions. Similarly, the inclusion of legumes can reduce the need for N fertilizers by promoting biological N fixation and decreasing N losses. Thus, even though the present study did not demonstrate this effect, the agronomic advantages of these practices may be more evident in systems with higher legume participation in the canopy and more intensive irrigation (28).
In addition to the N returned during winter and spring, 29 % of the total N return originated from maize crop residues, representing 98 kg ha-1 N retained in 10,976 kg ha-1 of straw, which remains in the soil and is available for decomposition and mineralization by the subsequent crop. In this context, it can be inferred that the amount of N supplied via fertilizers was sufficient to meet the demands of both winter/spring meat production and summer maize production. However, the actual balance can only be quantified by considering the N present in the soil and residues, as this constitutes the portion remaining in the system to be made available and utilized by the subsequent crop in ICLS.
The N exported by maize was similar among treatments. By adding the N exported by maize to the N returned to the soil, the total measured N in the system was, on average, 430 kg ha-1. Although this does not represent the exact amount of N atoms cycled through the system, due to the dynamic nature of the nutrient, these values allow for an assessment of nutrient utilization and comparisons across different management practices regarding N use efficiency. Of the 430 kg ha-1 total N measured in the system, 18 % originated from pasture residues, 28 % from urine, and 9 % from feces, which together account for the winter total of 237 kg ha-1, corresponding to 55 % of the total N in the system over the evaluation period (Figure 2).
Considering the total N applied as fertilizer throughout the experimental period (pasture + crops), 290 kg ha-1, and the total N returned, approximately 335 kg ha-1, one can note that the efficient use and maintenance of the nutrient within the system is essential, as the N returned exceeds the N applied. This occurs mainly due to the role of grazing animals in mobilizing N from pasture through grazing and recycling the nutrient via their excreta. As a result, N can be recycled multiple times within the system, enhancing its efficiency. Nevertheless, there is also a greater risk of losses, since N in feces and urine is more susceptible to loss than when retained in plant biomass.
4. Conclusion
The animals’ N intake during the winter was not affected by irrigation or the legume consortium. Similarly, N returned via post-grazing residues, fecal excretion, and urinary excretion per unit of live weight was not influenced by the treatments. Nevertheless, N return via urine per hectare was lower in treatments with irrigation associated with the legume, as well as in those without irrigation or legume. Maize grain yield was similar between irrigated and non-irrigated areas, as well as between areas with and without intercropping during the winter. Hence, our findings lead us to conclude that the use of irrigation and intercropping with vetch does not significantly alter the total amount of N returned and cycled within the system, which exhibited an average value of 335.61 kg ha-1.
Data availability statement
Data will be made available on request to the corresponding author.
References
-
1 Carvalho PCF, Souza ED, Denardin LGO, Kunrath TR, Machado DR, Souza Filho W, Martins AP, Tiecher T. Reconnecting nature and agricultural production: mixed cropping systems as a way forward sustainable intensification. Boletim de Indústria Animal. 2021; 78. http://dx.doi.org/10.17523/bia.2021.v78.e11496
» http://dx.doi.org/10.17523/bia.2021.v78.e11496 -
2 Franzluebbers AJ, Hendrickson JR. Should we consider integrated crop-livestock systems for ecosystem services, carbon sequestration, and agricultural resilience to climate change? Agronomy Journal. 2024; 116: 415-432. http://dx.doi.org/10.1002/agj2.21520
» http://dx.doi.org/10.1002/agj2.21520 -
3 Szymczak LS, Carvalho PCF, Lurette A, Moraes A, Nunes PAA, Martins AP, Moulin CH. System diversification and grazing management as resilience-enhancing agricultural practices: The case of crop-livestock integration. Agricultural Systems. 2020, 184. 102904. http://dx.doi.org/10.1016/j.agsy.2020.102904
» http://dx.doi.org/10.1016/j.agsy.2020.102904 -
4 Nunes PAA, Laca EA, Carvalho PCF, Souza Filho W, Kunrath TR, Martins AP, Gaudin A. Livestock integration into soybean systems improves long-term system stability and profits without compromising crop yields. Scientific reports. 2021,11, 1649. http://dx.doi.org/10.1038/s41598-021-81270-z
» http://dx.doi.org/10.1038/s41598-021-81270-z -
5 Iteba JO, Hein T, Singer GA, Masese FO. Livestock as vectors of organic matter and nutrient loading in aquatic ecosystems in African savannas. PLoS ONE. 2021, 16. e0257076. http://dx.doi.org/10.1371/journal.pone.0257076
» http://dx.doi.org/10.1371/journal.pone.0257076 - 6 Assmann TS, Soares AB, Assmann AL, Huf FI, Lima RCD. Adubação de sistemas em integração lavoura-pecuária. In: Jahmour J, Assmann TS (Orgs.). I Congresso Brasileiro de Sistemas Integrados de Produção Agropecuária e IV Encontro de Integração Lavoura-Pecuária no Sul do Brasil. Pato Branco: UTFPR Câmpus Pato Branco, 2017. p. 67-84.
-
7 Sanches AC, Gomes EP, Rickli ME, Fasolin JP, Soares MRC, Goes RHTB. Produtividade e valor nutritivo do capim Tifton 85 irrigado e sobressemeado com aveia. Revista Brasileira de Engenharia Agrícola e Ambiental. 2015, 19. 126-133. http://dx.doi.org/10.1590/1807-1929/agriambi.v19n2p126-133
» http://dx.doi.org/10.1590/1807-1929/agriambi.v19n2p126-133 -
8 Sah RP, Chakraborty M, Prasad K, Pandit M, Tudu VK, Chakravarty MK, Narayan SC, Rana M, Moharana D. Impact of water deficit stress in maize: Phenology and yield components. Scientific reports. 2020, 10. 2944. http://dx.doi.org/10.1038/s41598020-59689-7
» http://dx.doi.org/10.1038/s41598020-59689-7 - 9 Empresa Brasileira de Pesquisa Agropecuária - EMBRAPA. Sistema brasileiro de classificação de solos. 5.ed. Brasília (DF): Embrapa; 2018. 355p.
-
10 Alvares CA, Stape JL, Sentelhas PC, Gonçalves JLM, Sparovek G. Köppen’s climate classification map for Brazil. Meteorologische Zeitschrif. 2013, 22. 711-728. http://dx.doi.org/10.1127/0941-2948/2013/0507
» http://dx.doi.org/10.1127/0941-2948/2013/0507 - 11 Euclides VPB, Macedo MCM, Oliveira MP. Avaliação de diferentes métodos de amostragem [para se estimar o valor nutritivo de forragens sob pastejo]. Revista Brasileira de Zootecnia. 1992, 21. 691-702.
-
12 Tilley JMA, Terry RA. A two-stage technique for the in vitro digestion of forage crops. Grass and Forage Science. 1963, 18. 104-111. http://dx.doi.org/10.1111/j.1365-2494.1963.tb00335.x
» http://dx.doi.org/10.1111/j.1365-2494.1963.tb00335.x - 13 Myazawa M, Pavan MM, Muraoka T, Carmo CAFS, Melo WJ. Análise química de tecido vegetal. In: Silva FC (Ed.). Manual de análises químicas de solos, plantas e fertilizantes. 2.ed. Brasília: Embrapa Informação Tecnológica, 2009. p.199-233.
-
14 Myers WD, Ludden PA, Nayigihugu V, Hess BW. Technical Note: A procedure for the preparation and quantitative analysis of samples for titanium dioxide. Journal Of Animal Science. 2004,82. 179-183. http://dx.doi.org/10.2527/2004.821179x
» http://dx.doi.org/10.2527/2004.821179x -
15 Chizzotti ML, Valadares Filho SC, Valadares RFD, Chizzotti FHM, Tedeschi LO. Determination of creatinine excretion and evaluation of spot urine sampling in Holstein cattle. Livestock Science. 2008, 113. 218-225. http://dx.doi.org/10.1016/j.livsci.2007.03.013
» http://dx.doi.org/10.1016/j.livsci.2007.03.013 -
16 Raza A, Zahra N, Hafeez, MB, Ahmad M, Iqbal S, Shaukat K, Ahmad G. Nitrogen fixation of legumes: Biology and Physiology. In: Hasanuzzaman M, Araújo S, Gill S. (Eds). The Plant Family Fabaceae: Biology and Physiological Responses to Environmental Stresses. Springer; p.43-74, 2020. http://dx.doi.org/10.1007/978-981-15-4752-2_3
» http://dx.doi.org/10.1007/978-981-15-4752-2_3 -
17 Farias Filho JÁ, Moraes PVD, Artuso VA, Chiavon JAD, Silva DW, Kunz AG, Zanini WR. Competitive effect between bristle oat (Avena strigosa) and common vetch (Vicia sativa) plants in consortium under diverse populational densities. Journal of Agronomy. 2016,15. 184-190. http://dx.doi.org/10.3923/ja.2016.184.190
» http://dx.doi.org/10.3923/ja.2016.184.190 -
18 Koenig KM, Beauchemin KA. Nitrogen metabolism and route of excretion in beef feedlot cattle fed barley-based backgrounding diets varying in protein concentration and rumen degradability1,2. Journal of Animal Science. 2013, 91. 2295- 2309. http://dx.doi.org/10.2527/jas.2012-5652
» http://dx.doi.org/10.2527/jas.2012-5652 -
19 Angelidis A, Crompton L, Misselbrook T, Yan T, Reynolds CK, Stergiadis S. Evaluation and prediction of nitrogen use efficiency and outputs in faeces and urine in beef cattle. Agriculture, Ecosystems and Environment. 2019, 280. 1-15. http://dx.doi.org/10.1016/j.agee.2019.04.013
» http://dx.doi.org/10.1016/j.agee.2019.04.013 -
20 Garcia L, Dubeux JR JCB, Sollenberger LE, Vendramini JMB, Dilorenzo N, Santos ERS, Jaramillo DM, Moreno MR. Nutrient excretion from cattle grazing nitrogen-fertilized grass or grass-legume pastures. Agronomy Journal. 2021, 113. 3110-3123. http://dx.doi.org/10.1002/agj2.20675
» http://dx.doi.org/10.1002/agj2.20675 -
21 Selbie DR, Buckthought LE, Shepherd M.A. The challenge of the urine patch for managing nitrogen in grazed pasture systems. Advances in Agronomy. 2015, 129. 229-292. http://dx.doi.org/10.1016/bs.agron.2014.09.004
» http://dx.doi.org/10.1016/bs.agron.2014.09.004 -
22 Chadwick DR, Cardenas LM, Dhanoa MS, Donovan N, Misselbrook T, Williams JR, Thorman RE, McGeough KL, Watson CJ, Bell M, Anthony SG, Rees RM. The contribution of cattle urine and dung to nitrous oxide emissions: Quantification of country specific emission factors and implications for national inventories. Science of The Total Environment. 2018, 635. 607-617. http://dx.doi.org/10.1016/j.scitotenv.2018.04.152
» http://dx.doi.org/10.1016/j.scitotenv.2018.04.152 -
23 Lessa ACR, Madari BE, Paredes DS, Boddey RM, Urquiaga S, Jantalia CP, Alves BJR. Bovine urine and dung deposited on Brazilian savannah pastures contribute differently to direct and indirect soil nitrous oxide emissions. Agriculture, Ecosystems and Environment. 2014,190. 104-111. http://dx.doi.org/10.1016/j.agee.2014.01.010
» http://dx.doi.org/10.1016/j.agee.2014.01.010 -
24 Gao J, Luo J, Lindsey S, Shi Y, Wei Z, Wang L, Zhang L. Effects of boric acid on urea-N transformation and 3,4-dimethylpyrazole phosphate efficiency. Journal of the Science of Food and Agriculture. 2021, 6. 1091-1099. http://dx.doi.org/10.1002/jsfa.10719
» http://dx.doi.org/10.1002/jsfa.10719 -
25 Simon PL, Klein CAM, Zanatta JA, Van der Weerden TJ, Ramalho B, Bayer C. Nitrous oxide emission factors from cattle urine and dung, and dicyandiamide (DCD) as a mitigation strategy in subtropical pastures. Agriculture, Ecosystems and Environment. 2018, 267. 74-82. http://dx.doi.org/10.1016/j.agee.2018.08.013
» http://dx.doi.org/10.1016/j.agee.2018.08.013 - 26 Ledgard, SF.; Steele, KW. Biological nitrogen fixation in mixed legume/grass pastures. Plant and soil, v. 141, p. 137-153, 1992.
- 27 Sociedade Brasileira de Ciência do Solo (SBCS). Fertilidade do Solo: manual de adubação e de calagem para os Estados do Rio Grande do Sul e de Santa Catarina. 10.ed. Porto Alegre: Comissão de Química e Fertilidade do Solo, 2004.
-
28 Kakraliya SK, Singh U, Bohra A, Choudhary KK, Kumar S, Meena RS, Jat ML. Nitrogen and legumes: a meta-analysis. In: Meena R, Das A, Yadav G, Lal R. (Eds). Legumes for soil health and sustainable management, Springer, p. 277-314, 2018. http://dx.doi.org/10.1007/978-981-13-0253-4_9
» http://dx.doi.org/10.1007/978-981-13-0253-4_9
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Editor: Rondineli P. Barbero
