Soil water content beneath summer-dormant and summer-active swards in a seasonally semi-arid environment

Snaydon, R. W.

doi:10.1016/0002-1571(72)90037-4

Cited by 14 publications

(6 citation statements)

References 32 publications

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“…Even after the relatively wet summers in the third and fourth growing season, the maximum SMD was still larger than the normal winter moisture surplus that is potentially available to enable the FC to be reached before the next summer. The lack of full recharge to field capacity also has been reported for pasture and tree crops in sub-humid or semiarid environments (Snaydon 1972;Myers and Talsma 1992). If lack of recharge to full field capacity in the deeper soil occurred over a number of years, then there may be little advantage to deep rooted species such as lucerne or radiata pine.…”

Section: Winter Recharge and Drainage Lossesmentioning

confidence: 89%

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Soil moisture and water use by pastures and silvopastures in a sub-humid temperate climate in New Zealand

Pollock

Mead²,

McKenzie

2008

Agroforest Syst

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Soil moisture content from 0 to 2 m depth was monitored under 2-6 year old radiata pine (Pinus radiata) with three understoreys of bare ground, lucerne (Medicago sativa) and ryegrass/clover (Lolium perenne/Trifolium spp.) and under adjacent opengrown lucerne and ryegrass/clover pastures. By the fifth year soil moisture depletion/recharge pattern under the trees alone was similar to that under open pasture and under trees with pasture understoreys. Maximum plant available moisture storage was 207-223 mm in the top meter of this Templeton silt loam soil but only 69-104 mm at 1-2 m depth where coarse textures often predominated. Lucerne reduced soil moisture content (SMC) to lower levels during drier summers and extracted more water from 1 to 2 m depth than ryegrass/clover. Evapotranspiration (ET) during early summer when soil moisture was high was close to the Penman potential evapotranspiration (E p ), but the difference increased when SMC in the top meter dropped below 200 mm. The silvopasture treatments had higher ET in winter than pasture alone but this was still less than E p . Soil moisture deficits (SMD) at the end of each summer were sufficiently large to require slightly higher than normal winter rainfall and ET \ E p to recharge the soil to field capacity before the next summer. The soil moisture results, taken together with root and growth data, suggest that trees and understorey pastures are complementary in the first three or four growing seasons but this balance subsequently declines in favor of the pine trees. Management options, to extend the period that understorey pastures are productive, include reducing tree stockings, more vigorous pruning, using competitive understoreys and changing from pines to deciduous trees. Research on new silvopastoral combinations is suggested.

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Section: Winter Recharge and Drainage Lossesmentioning

confidence: 89%

“…Other studies have confirmed that sward or pasture type has had no effect on total seasonal water use in sub-humid or semiarid environments (Snaydon 1972;McKenzie et al 1990). Exceptions are where deeper rooted species have access to potentially more soil moisture if previous precipitation has recharged the deeper layer.…”

Section: Evapotranspirationmentioning

confidence: 93%

Soil moisture and water use by pastures and silvopastures in a sub-humid temperate climate in New Zealand

Pollock

Mead²,

McKenzie

2008

Agroforest Syst

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“…While there are some studies comparing seasonal water use of phalaris with other species (Snaydon 1972, Ridley et al. 1997, Lolicato 2000, Stork and Jerie 2003), no work has yet been published which compares a summer‐active with a summer‐dormant phalaris.…”

Section: Discussionmentioning

confidence: 99%

Summer Dormancy in Phalaris aquatica L., the Influence of Season of Sowing and Summer Moisture Regime on Two Contrasting Cultivars

Norton

Lelièvre

Volaire

2011

J Agronomy Crop Science

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A series of trials to increase understanding of the summer dormancy trait in Phalaris aquatica was conducted. Autumn‐sown and younger, spring‐sown plants of two cultivars (cvv), known to contrast in expression of summer dormancy, were established and then tested over the following summer under three moisture regimes: long drought; drought + mid‐summer storm; or full irrigation. The autumn‐sown plants of cv. Atlas PG expressed substantial but incomplete summer dormancy under all moisture regimes and exhibited the characteristic responses including significant growth reduction and herbage senescence. The summer‐dormant cv. Atlas PG used 31 mm less soil water over the summer and also began to rehydrate its leaf bases from conserved soil water before the drought broke. The non‐dormant cv. Australian grew whenever moisture was applied and also responded to the mid‐summer storm with a decline in dehydrin expression in leaf bases, whereas no decline occurred in Atlas PG, presumably because it remained dormant. The irrigated, younger, spring‐sown swards of cv. Atlas PG had restrained growth and produced only about 37 % of the herbage of cv. Australian. Drought reduced activity and growth of young plants of both cultivars but while Australian regrew in response to the storm, cv. Atlas PG, grew much less (59 % of Australian) indicating that dormancy, although only partially expressed after spring sowing, was reinforced by summer drought. Australian used more soil water over summer than Atlas PG, and it is suggested that this is why cv Australian is limited to the higher rainfall zones of south‐eastern Australia, particularly where soil water holding capacity is limited.

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“…Their need to transpire water freely during their seasons of active growth means they depend to a greater extent on current rainfall to meet their water requirements because stored soil water is rapidly expended (Snaydon 1972;Johns & Lazenby 1973a;Guobin & Kemp 1992). If their obligate need for adequate moisture is not met their persistence declines, especially during extended dry periods (Pook & Costin 1970;Brownlee 1973;Peake et al 1975;Wolfe & Southwood 1980).…”

Section: Some Ecological Impacts Of Pasture Improvement and Grazingmentioning

confidence: 99%

The place of C4grasses in temperate pastures in Australia

Johnston

1996

New Zealand Journal of Agricultural Research

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This paper explores the potential role of summer-active C 4 grasses in temperate areas in Australia from an ecological perspective. The main functional differences between C3 and C4 plants are briefly outlined. Taken together, the characteristics and environmental requirements of introduced C3 perennial pasture cultivars lessen their natural competitive ability except in well-watered and cool habitats. C4 plants are more competitive under conditions of high temperature and solar radiation. Within the C4 group, grasses belonging to the subfamily Panicoideae usually prefer humid, wet environments and generally decline in importance with increasing grazing pressure and increased soil nitrogen (N) levels. Genera of Eragrostoideae generally prefer hot, dry habitats; they increase in dominance with increased grazing pressure and N availability. These responses give the C4 group as a whole a wider adaptive range and at the community level provide versatility in responses to changed conditions such as grazing. Based on their preferred zones of natural distribution, it appears that introduced C3 pasture species are sown widely outside the area where they would be favoured to persist. The ecological impacts of grazing by domestic livestock and pasture improvement are briefly outlined with particular emphasis on changes in botanical composition. There are similarities between changes in Australian grasslands and those reported in South Africa. It is concluded that species which naturally increase in A96012 Received 15 January 1996; accepted 10 July 1996 abundance in grazed pastures (such as some genera of Eragrostoideae) would offer considerable advantages for the development of naturally sustainable pastures. Such pasture species would offer a number of side-benefits including reduced rates of pH decline and deep drainage of excess water to water tables. These two problems represent major threats to agricultural sustainability in the temperate zone and both result from the inability of C 3 grass-based pastures to grow actively in summer.

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Soil water content beneath summer-dormant and summer-active swards in a seasonally semi-arid environment

Cited by 14 publications

References 32 publications

Soil moisture and water use by pastures and silvopastures in a sub-humid temperate climate in New Zealand

Soil moisture and water use by pastures and silvopastures in a sub-humid temperate climate in New Zealand

Summer Dormancy in Phalaris aquatica L., the Influence of Season of Sowing and Summer Moisture Regime on Two Contrasting Cultivars

The place of C4grasses in temperate pastures in Australia

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