Responses of Cynodon pastures mixed with forage peanut in Southwestern Paraná, Brazil

ARTIGOS/ARTICLES DOI: 10.5433/1679-0359.2016v37n6p4193

ZOOTECNIA

Responses of Cynodon pastures mixed with forage peanut in Southwestern Paraná, Brazil Respostas de pastagens do gênero Cynodon consorciadas com amendoim forrageiro no Sudoeste do Paraná Magnos Fernando Ziech1*; Clair Jorge Olivo2; Ana Regina Dahlem Ziech1; Gilmar Roberto Meinerz3; Alberto Luiz Gagstetter4; Jacson Rodrigo Cullmann4 Abstract The genus Cynodon includes a number of grasses cultivars important for dairy farms. Although Cynodon grasses are usually established as single crops, multi-cropping them with legumes can yield important benefits such as significant reduction on fertilizer costs, increased soil fertility and the nutritional value of the forage. Therefore, the aim of this study was to evaluate the development, and the botanical and structural components of Coastcross-1 and Tifton 85 pastures cultivated over a period of two years (planting in August 2011, last cut in April 2013) with increasing inclusion of forage peanut (0, 25, 50 and 75% planted area). The experimental design was randomized blocks, with eight treatments (pastures) and split plot (seasons), with three replicates. Measured parameters included forage mass, dry matter accumulation rate, leaf:stem ratio, dead material, and other species and forage peanut mass. The different peanut inclusion rates did not affect the pasture production parameters or the structural composition of the cultivars. With 75% of the area planted with forage peanut, the legumes represented close to 30% of the total mass. The leaf:stem ratio was highest for Tifton 85 in milder daily average temperatures, although, in this situation, both cultivars decreased the forage rate accumulation. Increasing the percentage of area planted with forage peanut also increased the participation of legumes, without interfering with the presence of dead material or other species. Key words: Arachis pintoi. Coastcross-1. Forage mass. Forage accumulation rate. Tifton 85.

Resumo O gênero Cynodon inclui uma série de cultivares de gramíneas importantes para a exploração leiteira. Embora essas gramíneas sejam normalmente estabelecidas singularmente, o consórcio com leguminosas pode trazer benefícios importantes, como a redução significativa nos custos de fertilizantes, aumento da fertilidade do solo e do valor nutritivo da forragem. Portanto, o objetivo do estudo foi avaliar o desenvolvimento, os componentes estruturais e botânicos de pastagens de Coastcross-1 e Tifton 85 consorciadas com amendoim forrageiro (0, 25, 50 e 75% da área implantada), submetidas a cortes, entre agosto de 2011 (plantio das pastagens) e abril de 2013 (último período de corte), totalizando dois anos de estudo. O delineamento experimental foi de blocos ao acaso, com oito tratamentos (pastagens) e parcelas subdivididas no tempo (estações), com três repetições. Avaliou-se a massa de forragem, a taxa de acúmulo de massa seca, a relação folha:colmo, o material morto, outras espécies e a massa de amendoim forrageiro. Os distintos porcentuais de área implantada com amendoim forrageiro não Profs. Drs., Universidade Tecnológica Federal do Paraná, UTFPR, Santa Helena, PR, Brasil. E-mail: [email protected]; ana. [email protected] 2 Prof. Dr., Universidade Federal de Santa Maria, UFSM, Santa Maria, RS, Brasil. E-mail: [email protected] 3 Prof. Dr., Universidade Federal da Fronteira Sul, UFFS, Cerro Largo, RS, Brasil. E-mail: [email protected] 4 Discentes, UTFPR, Dois Vizinhos, PR, Brasil. E-mail: [email protected]; [email protected] * Author for correspondence 1

Received: Oct. 16, 2014 – Approved: Sept. 20, 2016

Semina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 4193-4202, nov./dez. 2016

4193

Ziech, M. F. et al.

afetaram os parâmetros produtivos da pastagem e da composição estrutural das cultivares. A utilização de 75% da área de plantio com amendoim forrageiro promoveu participação próxima a 30% de leguminosa na massa de forragem total. A relação folha:colmo foi superior para a cultivar Tifton 85 em temperaturas médias diárias mais amenas. Nessa condição, ambas as cultivares diminuíram a taxa de acúmulo de forragem. O percentual crescente de área implantada com amendoim forrageiro aumentou a participação da leguminosa, não interferindo quanto a presença de material morto e outras espécies. Palavras-chave: Arachis pintoi. Coastcross-1. Massa de forragem. Taxa de acúmulo de forragem. Tifton 85.

Introduction

Materials and Methods

The genus Cynodon includes a number of cultivars that are important for dairy farms, especially due to their perenniality, rapid establishment and high forage mass production. These grasses are usually established as single crops and, because of their potential, require high levels of fertilization, especially with nitrogen, resulting in high production costs. The use of legumes in this kind of pasture can reduce spending on fertilizers and improve pastoral environment, soil fertility and the nutritional value of the forage (BARCELOS et al., 2008). Among legumes, stoloniferous forage peanut stands out for its durability, forage production capacity and potential for improving animal performance (BARBERO et al., 2010).

This study was conducted in an experimental area next to the Dairy Farming Teaching and Research Unit (UNEPE) of the Universidade Tecnologica Federal do Paraná, Dois Vizinhos campus, located at 25°44” S 53°04” W, at an average elevation of 520 m. Local soil is classified as Red distroferric nitisol (BHERING; SANTOS, 2008), and local climate is considered Cfa (humid subtropical, Koppen climate classification), without a well-defined dry season, and with 22°C average temperature in the hottest month.

Legumes usually have a slow growth rate, especially as compared to Cynodon grasses, which have rapid establishment and high productivity. In fact, previous studies on multi-cropping forage peanut with Cynodon grasses have stumbled on difficulties to maintain adequate levels of participation of this legume in the pasture (PARIS et al., 2008). Thus, multi-cropping success appears to be associated with the establishment of the pastures and planting a larger area with legumes could result, once the multi-crop is established, in a 25–30% participation of the legume in forage mass, resulting in higher sustainability of the forage system. Thus, the aim of with this study was to evaluate the effects of inclusion of stoloniferous forage peanuts multicropped with Coastcross-1 or Tifton 85 grasses on the development and botanical and structural composition of the grass, over two years, in the southwestern Paraná (PR) region of Brazil.

The area used for the experiments was approximately 400 m2, with two cultivars of the genus Cynodon (Tifton 85 and Coastcross-1). At the time of planting, we introduced increasing percentages (0%, 25%, 50% and 75%) of a legume of the genus Arachis (stoloniferous forage peanut, cv. Amarillo) in the occupied area. The planted pastures were divided in 2 x 6 m parcels. Planting was from seedlings, spaced linearly 33 cm apart, in rows 50 cm apart, in 3 replicates. Each Cynodon cultivar was planted in four arrangements: Cynodon cultivar alone; Cynodon cultivar in 3 successive rows and forage peanut in one (allowing 25% of the area for the legume); Cynodon cultivar and forage peanut, each in 2 successive rows (50% legume); and Cynodon cultivar in 1 row and forage peanut in 3 successive rows (75% legume). Before pasture planting, weeds were controlled through manual weeding and desiccation. When the experiment started, soil analysis (0–20 cm depth) was performed for the following parameters:

4194 Semina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 4193-4202, nov./dez. 2016

Responses of Cynodon pastures mixed with forage peanut in Southwestern Paraná, Brazil

pH (H2O) = 5.5; OM (%) = 3.9; Clay (%) = 54; Mehlich-P (mg/L) = 4.5; K (mg/L) = 72; Ca (cmolc/L) = 8.8; Mg (cmolc/L) = 3.4; H+Al (cmolc/L) = 3.5; effective CTC (cmolc/L) = 12.6; Al Saturation (%) = 0.0; Base saturation (%) = 78.2. Based on the chemical analysis and on CQFS RS/ SC (2004) recommendations for multi-cropping of grasses and tropical legumes, we applied 2.2 ton. ha-1 lime (filler – PRNT >90%) before planting. Fertilization during pasture planting was 110 kg.ha-1 P2O5 and 60 kg.ha-1 K2O, in the first year, and 60 kg.ha-1 for both P2O5 and K2O, in the second year. To support the establishment of Arachis in the multi-crops, we supplied 80 kg.ha-1.yr-1 nitrogen (N) during planting, avoiding losses in biological N fixation (THOMAS, 1994). In the second year, 20 kg.ha-1 N was applied every two cuts (CQFS RS/ SC, 2004) totaling 60 kg.ha-1 N over all treatments. This study was conducted between September 3, 2011 (planting) and April 14, 2013 (final cut), for a total of 588 days. Pastures were mowed whenever the grass reached between 20 and 25 cm, totaling fourteen collections in the period, averaged for each season. For every collection, a 1m2 area, representing the proportion of each multi-crop, was randomly selected for cutting at 7 cm above the soil. Afterwards, another cut close to the ground was performed for measurement of the residual mass within a rectangular area of 0.25 m² (1.0 x 0.25 m). Then, the rest of the experimental area was mowed down to a 7 cm height with a sickle, and the residue was removed from the experimental unit with rakes. After cutting, the samples were weighed, homogenized, subsampled and separated by species to determine botanical composition. The structural components of the grasses were also separated in

leaf blade, stem and dead material + senescent. To determine the dry matter percentage (DM) of each component, the samples were weighed and dried in a forced air furnace at 60°C until constant weight. The accumulation ratio was obtained by the equation (MFT – MFR)/PD, where, MFT = the total forage mass for each cutting period; MFR = mass of residual forage for the previous cut and PD = rest period in days. Rainfall and average air temperature data, recorded by the INMET weather station at UNEPE, were collected during the evaluation period (Figure 1). Recorded average temperature and rainfall values were similar to annual averages. The experimental design was randomized blocks, with eight treatments (formed pastures) and three replicates (plots) in split plot (seasons in which collections were performed). Data were subjected to analysis of variance and polynomial regression, with a 5% significance level (p = 0.05). Analyses were performed using the statistical software Genes (CRUZ, 2006) and the means were compared by the Tukey test. The statistical model for the analysis of the variables of the pasture was represented by Yijk = μ + Pi + Bj + Eij (Error A) + Sk + Psik + εijk (Error B), where Yijk is the dependent variables; i, treatments index (pastures); j, repetition rate; and k, index of split plot (seasons). μ is the mean of all observations; Pi is the effect of pastureland; Bj is the effect of the blocks; Eij is the effect of grazing within the plots (error A); Sk is the effect of the seasons; Psik is the effect of the interaction between grassland and stations, and εijk corresponds to the residual experimental error.

4195 Semina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 4193-4202, nov./dez. 2016

Ziech, M. F. et al. Figure 1. Average monthly temperature (°C) and rainfall (mm). Dois Vizinhos, PR, Brazil, 2013.

Figure 1. Average monthly temperature (°C) and rainfall (mm). Dois Vizinhos, PR, Brazil, 2013.

400

Rainfall (mm) Average Temperature (ºC)

30

375 325

25

300

Rainfall (mm)

275 250

20

225 200

15

175 150 125

10

100 75 50

Average Temperature (ºC)

350

5

25 0

1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 /2 p/2 t/2 v/2 c/2 n/2 b/2 r/2 r/2 y/2 n/2 l/2 g/2 p/2 t/2 v/2 c/2 n/2 b/2 r/2 r/2 y/2 g u c o c o e a p a a p a Au Se O N D Ja Fe M A M Ju J Au Se O N De Ja Fe M A M

0

Source: Instituto Nacional de Meteorologia – Automatic weather station at Dois Vizinhos, PR, Brazil. Source: Instituto Nacional de Meteorologia – Automatic weather station at Dois Vizinhos, PR, Brazil.

Results Results and Discussion and Discussion

was similar among all formed pastures. During winter, Tifton 85 developed slower, failing to attain In the first year (beginning on December In the first year (beginning on December7, 7, 2011) eight cuts were made at day 95 after planting: 1 the minimum height for cutting. Thus, Coastcross-1 2011) eight cuts were made at day 95 after planting: in spring, 3 in summer, 3 in fall and 1 in winter. In the second on October six cuts capacity seemsyear to(beginning have the highest8, 2012) production 1 in spring, 3 in summer, 3 in fall and 1 in winter. In were made: 3 in spring, 2 in summer and 1 in fall, and harvest ended intemperatures. late April. More Over cuts were in milder theperformed seasons, higher the second year (beginning on October 8, 2012) six in the first year because the winter was milder than responses in the secondwere year,observed with fewerfor frosts and higher year due the second cuts weretemperatures. made: 3 inFrosts spring, 2 in summer and 1 in in mid-May of the second year impacted development the sward, preventing winter greater to complete soilofcoverage and consequent fall, and harvest ended in late April. More cuts were cuts. tillering. performed in the first year because the winter was The available forage mass was affected by the interaction between multi-crop proportion and The mass of residual forage was also significantly milder than in the second year, with fewer frosts season, as shown in Table 1. In the first evaluation period (spring 2011), both grass cultivars combined with and higher temperatures. Frosts in mid-May of the affected (p