Characterization of Dairy Slurry in Southern Chile Farms
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INVESTIGACIÓN CHARACTERIZATION OF DAIRY SLURRY IN SOUTHERN CHILE FARMS Caracterización de purines de lecherías en el Sur de Chile Francisco Salazar1*, Juan Carlos Dumont1, David Chadwick2, Rodolfo Saldaña1 y Mabel Santana1 A B S T R A C T R E S U M E N In this study 50 slurry samples were collected from En este estudio se colectaron 50 muestras de purines commercial dairy farms located in the South of Chile de predios lecheros ubicados en el Sur de Chile (X during 1995-1997. Samples were analyzed for dry Región). Las muestras fueron analizadas para deter- matter, pH, organic matter, available and total macro minar materia seca, pH, materia orgánica, macro nu- nutrients (nitrogen, phosphorus, potassium, calcium, trientes totales y disponibles (nitrógeno, fósforo, po- magnesium and sodium), available and total micro- tasio, calcio, magnesio y sodio). También se analiza- nutrients (zinc, iron, manganese and copper) and total ron micronutrientes disponibles y totales (zinc, hie- aluminum. Results showed that the dry matter content rro, manganeso y cobre) y aluminio total. Los resul- in dairy effluents was low, with 62% of the samples tados permitieron determinar que los purines tenían being < 4% DM. This reflected the large volumes of un bajo contenido de materia seca, ya que 62% de las water that the storage received. A great variation in muestras tenían menos de 4%. Esto refleja la gran nutrient content was observed in the analyzed samples, cantidad de agua que reciben los pozos de almacena- probably reflecting differences in feeding regimes, use miento. Se observó una gran variabilidad entre las of wash water, rainfall and age of slurry at the time of muestras colectadas, lo que puede ser explicado por sampling. In general, the concentration of macro and diferencias en la alimentación, uso de agua de lava- micronutrients was low. In the present study, the do, aguas lluvia y tiempo de almacenamiento del pu- dry matter in the slurry proved to be a good indicator rín. En general, la concentración de macro y micro- of some nutrients in the samples analyzed. Positive nutrientes fue baja. En el presente estudio, la materia correlations (p < 0.001) were obtained between dry seca del purín mostró ser un buen indicador de algu- matter content and total phosphorus (r2 = 89%), nos nutrientes analizados. Correlaciones positivas (p total calcium (r2 = 87%), total magnesium (r2 = 82%), < 0,001) fueron obtenidas entre la materia seca y el available phosphorus (r2 = 75%), ammonium nitrogen fósforo total (r2 = 89%), calcio total (r2 = 87%), (r2 = 68%), total potassium (r2 = 64%), available magnesio total (r2 = 82%), fósforo disponible (r2 = potassium (r2 = 60%), total nitrogen (r2 = 55%), total 75%), nitrógeno amoniacal (r2 = 68%), potasio total zinc (r2 = 74%), total manganese (r2 = 64%) and (r2 = 64%), potasio disponible (r2 = 60%), nitróge- total iron (r2 = 62%). Data from this study could be no total (r2 = 55%), zinc total (r2 = 74%), manga- used as a guideline to estimate nutrient contribution neso total (r2 = 64%) y hierro total (r2 = 62%). La from dairy slurry when applied to farmland. información de este estudio puede ser usada como base para estimar el aporte de nutrientes de purines al ser Key words: nutrients, dairy effluents, cattle slurry, aplicados en suelos agrícolas. farm waste. Palabras clave: nutrientes, efluentes de lechería, pu- rines bovinos, desechos ganaderos. 1 Instituto de Investigaciones Agropecuarias, Centro Regional de Investigación Remehue, Casilla 24-O, Osorno, Chile. E-mail: [email protected] *Autor para correspondencia. 2 Institute of Grassland and Environmental Research, North Wyke, Okehampton, Devon, EX20 2SB, United Kingdom. Recibido: 29 de diciembre de 2006. Aceptado: 10 de mayo de 2006. AGRICULTURA TÉCNICA (CHILE) 67(2):155-162 (ABRIL-JUNIO 2007) 156 AGRICULTURA TÉCNICA - VOL. 67 - No 2 - 2007 INTRODUCTION al., 1999; MAFF, 2000), pig slurry and chicken manure (Nicholson et al., 1999; MAFF, 2000), fish Milk production has increased steadily in Chile manure (Salazar and Saldaña, 2007) and sewage during the last years (ODEPA, 2005). This growth sludge (Arata, 2005). has resulted from intensification of production systems, which rely on a higher use of concentrates, Farmers from European countries have been fertilizers, forage and silage. With regard to encouraged to analyze slurry before applying it to livestock management, partial or total confinement land, either by use of on-farm tests or by submitting systems have become common, resulting in a high samples to commercial laboratories (Van Kessel et concentration of animals generating large volumes al., 1999; Williams et al., 1999). There are also of organic waste (slurry, dirty water and farmyard tables of compiled information about nutrient manure) in a limited land area. content of different types of animal slurry: dairy cattle, beef cattle, pigs, chickens, and other organic The South of Chile has suitable climatic conditions wastes (MAFF, 2000). In addition, computer and soil types for cattle production, where programs have been developed to help estimate production systems are based principally in natural nutrient contribution from manures by using and improved pastures. The Lake Region (Región information from farmers (Schmitt et al., 1997; de Los Lagos) (39º to 44º S; 71º to 73º W) Chambers et al., 1999). This information allows concentrate 56% of the national cattle herd, and farmers to make a more rational use of slurry, so that produce 70% of the country’s milk (ODEPA, 2005). they can control the applied doses and balance them In addition, 80% of the dairy farmers are located with commercial fertilizers to satisfy crop needs. in this region and they own 67% of the land dedicated to dairy production, on a national basis Although the use of farmyard manure and dairy (Anrique, 1999). slurry are a common practice among Chilean farmers, there is a lack of information about the The most common confinement systems in the South macro and micronutrients contents of these of Chile are straw-based systems and housing materials. The objective of this study was to systems (Salazar et al., 2003); the latter producing characterize chemically the slurry from dairy farms effluents and slurry. Slurry is a mixture of livestock in the South of Chile, and to compare them with faeces and urine, diluted with rainfall or cleaning the values published in the literature. water, and may contain a small proportion of remains of bedding, normally used in dairy cattle buildings, MATERIALS AND METHODS and feeds (Pain and Menzi, 2003). In appearance, it is a liquid material that can be pumped and that During 1995-1997 sampling was carried out on contains less than 15% of dry matter. slurry lagoons or slurry concrete tanks from 50 dairy farms located in the Region de Los Lagos (39º to Slurry is an important source of organic matter and 44º S; 71º to 73º W) of Southern Chile. The samples macro and micronutrients (Aguilera et al., 1995; were taken from dairy farms with housing and Chambers et al., 1999; Pain, 2000). An effective systems of slurry management and/or storage. Only management of dairy slurry should attempt to large and medium size dairy farms (over 100,000 L maximize economic benefits for the farmers milk yr-1farm-1) (Anrique, 1999) were chosen for through the implementation of adequate this study. management and utilization practices, as well as minimizing the risks of contamination of water Farms were visited in order to collect the samples courses, soil and air (Wouters and Verboon, 1993; during the housing period, between April and Archer and Marks, 1997). A key factor in the November. In addition, during the visit, a efficient utilization of slurry is to know its nutrient questionnaire was used to gather information about content and availability, which may be determined the management and utilization of slurry on each through an analysis of its chemical composition, farm (Salazar et al., 2003). as it has been reported for cattle slurry (Overcash et al., 1983; Aguilera et al., 1995; Menzi and Prior to sampling, the slurry was mixed within the Kessler, 1998; Demanet et al., 1999; Nicholson et storage with farm equipment, or at the sampling F. SALAZAR et al. - CHARACTERIZATION OF DAIRY SLURRY IN ... 157 point using a manual shaker in order to collect a (DTPA) micronutrient extraction method and AAS representative sample. A total of 2 L of slurry was as above according to the methodology revised by collected from four different points (North, South, Sadzawka (1990). East and West) of the slurry store. The sample was stored in a plastic container and refrigerated at < 4ºC The chemical data gathered were analyzed once it reached the laboratory. statistically, media ranges being calculated for each parameter. Linear regression analyses were also The samples were dried and grounded to a fine pow- carried out (GENSTAT, 1993) in order to establish der to ensure homogeneity before analysis. A frac- relationships between slurry nutrient content and tion of each manure sample was oven dried until its dry matter content. constant weight at 105°C for dry matter determina- tion. Organic matter (OM) was determined by RESULTS AND DISCUSSION loss on ignition (550ºC, 6 h) in a muffle furnace according to AOAC (1984). Acidity (pH) was de- The results showed that the dry matter content in termined by electrometric method revised by slurry was generally low averaging 3.9% (range 0.2- Sadzawka (1990). 13.7), where almost 50% of the samples did not exceed 2%. These results are in agreement with the Total macronutrients P, K, Ca, Na and Mg, and to- data for dairy effluents from a farm located in South tal micronutrients Zn, Fe, Mn and Cu and total Al Chile collected by Aguilera et al. (1995) and with were determined by acid digestion according to the that of Longhurst et al.