Manitoba Agriculture, Food and Rural Initiatives

Importance of Litter Accumulation in Native and Tame
Pastures
ARDI 05-725
Final report

Prepared by Simon Neufeld (MSc candidate) and Martin Entz
Department of Plant Science, University of Manitoba
Other participants:  Matthew Wiens, University of Manitoba; Yuying Chen, Lanzhou University, Gansu province, China 

Executive Summary

                        Litter, defined as the dead plant material standing or lying on the soil surface, is considered beneficial in pastures primarily for its ability to conserve water.  Little previous research has been conducted on litter in Manitoba pastures.  In the first ever Manitoba pasture litter survey (conducted by the Manitoba Forage Council, Manitoba Agriculture, Food and Rural Initiatives, PFRA and the University of Manitoba), litter amount in native pasture averaged 1236 kg/ha.  However, many sites were well below this level, and below the minimum litter level recommended in Alberta (656 kg/ha). 

Figure 1. Locations of Litter Rate Study sites in southwest Manitoba

            The purpose of this study was to determine the effect of increasing litter amount on pasture yield, soil water conservation and soil temperature.  The study was conducted by Simon Neufeld, as part of his MSc program.   Litter experiments were conducted in five south central and south western locations in Manitoba.  Observations were conducted in two growing seasons – 2006 and 2007. 

 

            Results showed that litter consistently reduced soil surface temperature.  This observation clearly shows that litter reduces solar energy input into the surface soil.  Less solar energy reaching the soil surface means a lower potential for soil water evaporation.  Observations of litter effects on soil water were less consistent than litter effects for temperature.  When differences were observed, however, litter usually always increased soil water content.  In a few cases, litter actually reduced soil water content.  It is known that litter can reduce movement of water from light rains into soil, since the litter captures and holds the water. 

            In this study, litter failed to show any relationship with forage yield.  Longer-term studies are likely needed for the litter-forage yield relationship to be tested. 

             In conclusion, litter decreased surface soil temperature and sometimes increased soil water content.  Maintaining litter on the soil surface is deemed as beneficial to maximizing the water capture and water use efficiency in dryland pastures in SW Manitoba.