How does pig slurry fertilization influence percolated water and runoff erosion? A study of the soybean cycle in Brazilian Cerrado soil

Highlights

• Runoff was monitored during the soybean cycle after treatment with three different fertilizer sources.

• The 25 m^− 3 ha^− 1 pig slurry application showed high values of soil water infiltration.

• Fertilizer sources did not affect sediment, water ornutrient losses.

• Soybean yield was not affected by fertilizer source.

Abstract

The objective of this study was to evaluate the effects of pig slurry (PS) and chemical fertilizer (NPK 02–20–20) applications on soil water infiltration; sediment, water and nutrient losses by runoff; and soybean yield during a soybean (Glycine max L.) cropping cycle. A field study was carried out in Rio Verde, Goiás, Brazil on a Cerrado Oxisol managed with no tillage. The experiment was arranged as a randomized block design with three replications and treatments. The treatments consisted of two doses of PS, 25 and 100 m³ ha^− 1, and chemical fertilization at 370 kg ha^− 1 (NPK 02–20–20) applied to the soil surface in a single application. After the occurrence of rainfall events, the volume of percolated water in lysimeters and the sediment and water losses in plots was measured. To determine the macro and- (Ca, Mg, K, P) micronutrients (Fe, Mn, Cu, Zn), runoff water was collected. We also assessed the dry biomass and productivity of soybean production at the end of the experiment. Treatment with 25 m³ ha^− 1 of PS resulted in higher amounts of (106 mm) percolated water in the soil (p > 0.05). Neither losses of water, sediment and nutrients or biomass production and soybean productivity were significantly affected by the PS treatments compared with chemical (NPK) fertilization (p > 0.05). A trend of higher sediment and water losses was observed in the 25 m³ ha^− 1 PS treatment (249.86 kg ha^− 1 and 20.58 mm, respectively) compared with the 100 m³ ha^− 1 PS and chemical (NPK) treatments; the 25 m³ ha^− 1 PS treatment showed ~ 10% and ~ 43% higher values of sediment losses, respectively, and ~ 43% and ~ 23% higher values of water losses, respectively. Regarding soybean productivity, the 25 m³ ha^− 1 PS treatment showed a tendency of low productivity (3405 kg ha^− 1) that was ~ 15% and ~ 20% lower than that of the 100 m³ ha^− 1 PS and chemical (NPK) treatments, respectively. The low values of sediment and water required per kilogram of soybean produced in the chemical fertilization and 100 m³ ha^− 1 PS treatments indicate that these management regimes are more sustainable.

Introduction

In agricultural areas, the use of a new concept for increasing crop culture production has been increasing in recent years. Increased yields in crop cultures only occur when there is proper management of the cultivated area along with the use of resources offered by the field (Lourenzi et al., 2014). In the Rio Verde region (Goiás, Brazil), the adoption of no tillage management associated with the use of pig slurry (PS) to fertilize the main crop cultures of the Cerrado (soybean, corn, millet) has been increasing (Nunes et al., 2015, Penha et al., 2015, Santos et al., 2015).

The adoption of no tillage in the Cerrado region can be explained by the benefits that this management practice provides the soil, as it increases the amount of water that infiltrates the soil, increases organic matter, promotes the cycling of nutrients, and improves soil biological activity and fertility (Derpsch et al., 2010, Busari et al., 2015). On the other hand, the abundant use of PS to fertilize crops is related to the large supply of this organic waste provided by the development of agricultural industries in this region (IBGE – Instituto Brasileiro de Geografia e Estatística, 2015, Penha et al., 2015).

The use of PS as a source of nutrients may be an alternative for highly weathered Cerrado soils for supplying low contents of available nutrients (phosphorus–P, potassium–K, calcium–Ca, magnesium–Mg, sulfur–S, boron–B, copper–Cu, manganese–Mn and zinc–Zn) to these soils. Also, the use of PS in soils can contribute to the proper destination of waste generated from agricultural industries (Benke et al., 2008). Recycling waste such as PS by using it as soil fertilizer may improve the physical, chemical and biological characteristics, avoiding soil degradation in agricultural areas (Andreola et al., 2000, Scherer et al., 2007, Corrêa et al., 2011, Girotto et al., 2013, Penha et al., 2015).

A study conducted by Gunkel-Grillon et al. (2015) on Uvéa Island (South Pacific) reported that PS applications increase the content of macro- and micronutrients in a ferralitic soil, and this soil class was more compatible with a sustainable disposal management of PS than were calcareous soils. In Brazil, an earlier study by Lourenzi et al. (2014) demonstrated that the highest rate of PS application (80 m³ ha^− 1) increased nutrient availability during several years (especially P) in Santa Maria Rio Grande do Sul. The authors also observed the highest yield and accumulated dry matter of maize, and grain production was verified at the high dose of PS. Quadro et al. (2011) also indicated that C and N in the soil microbial biomass increased with a maximum dose of 18 m³ ha^− 1 of PS in Rio Grande do Sul, Brazil, whereas CO₂ evolution increased with a maximum application of 24 m³ ha^− 1. In Santa Catarina, Brazil, Mecabô Júnior et al. (2014) observed that a dose of 100 m³ ha^− 1 PS positively affected the physical properties of the soil and reduced the losses of soluble P and K in runoff.

Although the use of PS as a fertilizer is an alternative in agricultural areas (Lourenzi et al., 2014, Gunkel-Grillon et al., 2015, Oliveira et al., 2016), this practice should be studied with consideration of the following issues: the effects of this liquid waste on the soil; the correct dose to be used; the benefits to improving the soil regarding the reduction of erosion; and, in particular, the influence of this waste on crop productivity.

In this sense, the objective of this study was to evaluate the effects of PS application and chemical fertilizer (NPK 02–20–20) on soil water infiltration; sediment, water, and nutrient losses by runoff; and yield during a soybean cycle on a Cerrado Oxisol managed with no tillage.