Animal Forage, Commercial Farm Projects, Food Plants - Annual, Food Plants - Perennial, Fungi, Land, Livestock, Plant Systems, Rehabilitation, Salination, Soil Biology, Soil Composition, Soil Conservation, Structure — by Joel Dunn June 30, 2012
Harvesting oats as green native perennial pasture
grows up between the cereal rows (Seis, 2006)
Pasture cropping is a farmer-initiated land management system that seamlessly integrates cropping with pasture production, and allows grain growing to function as part of a truly perennial agriculture. Annual winter growing (C3) cereal crops are direct drilled into living summer growing (C4) perennial pasture grasses as the pasture sward enters the dormant phase of its growth cycle, allowing year-round growth and eliminating fallow and bare ground. This cereal production for grain and fodder is integrated with an intensive time controlled grazing system. There are important sustainability benefits of maintaining more perennial plants across agricultural landscapes, and the low input costs and flexible nature of the system make it attractive to producers.
Pasture cropping has already captured the imagination of the permaculture community because of its potential to make grain cropping compatible with permanent, regenerative agriculture. This review provides an in depth discussion of the development of pasture cropping systems in the NSW Central West, techniques and strategies of the system, environmental and economic factors, the dissemination of the technology around the Australian cereal-livestock zone, and potential future development and adoption.
1. Sustainability issues for annual cropping
Grains provide the bulk of most human staple diets around the world. Also, there is a strong argument that human diets that are more plant based than animal based require less consumption of energy and ecological resources, based on the use of lower trophic levels. It follows from all this that sustainable grain production is fundamental to sustainable agriculture and sustainable society. Unfortunately, there are numerous historical examples of grain based agricultural systems and the civilisations that depended on them failing as a result of soil degradation and erosion associated with cultivation for annual cropping (Montgomery, 2007).
Annual crops provide high levels of provisioning services (such as food) but low levels of regulating and supporting ecosystem services such as hydrological regulation, erosion control, water purification, nutrient cycling, etc. As such, major environmental consequences including salinisation of land and rivers, soil erosion, and flooding, are associated with broad-scale removal of perennial plants to make way for annual dominated agricultural systems (Roberts et al, 2009). These issues are evident in Australia — huge areas of cereal producing land suffer erosion, and/or are affected by rising groundwater and threatened by salinity as a result of clearing native perennial vegetation and replacing it with annual crops (George et al, 1997). Another significant negative effect of annual cropping is the soil damage caused by cultivation, including loss of organic carbon and increased susceptibility to erosion (Liu et al 2006). Accordingly, there has been a great loss of soil organic matter in the Australian cereal belt over the last fifty years, often exceeding a 60% loss in the upper topsoil layer (Dalal & Chan 2001).
No-till cropping provides better outcomes in terms of soil organic carbon in the top layers of soil and reducing erodibility, by decreasing disturbance and oxidation and slowing the rate of organic matter decomposition (Reicosky et al 1995). However, this technique does not address all the issues associated with dominance of annual plants in agricultural systems, as perennial plants still need to be excluded from annual cropping areas. It is also associated with heavy use of broad spectrum herbicides like glyphosate, which are the source of increasing concerns about environmental contamination and even human birth defects (Ho, 2010).
Pasture cropping, the planting of annual cereal crops into living perennial pasture, goes further towards more stable systems. With this technology, not only is soil disturbance low, but perennial plants are maintained, inter-cropped with the annual grain crop (Millar & Badgery 2009). Pasture cropping in suitable agroecological conditions has the potential to reduce and even reverse the environmental impacts associated with grain production by increasing soil organic carbon, increasing agro-biodiversity and improving hydrology (Bruce et al, 2005).
2. The history and development of pasture cropping systems
Pasture cropping in its current incarnation is a ‘new’ technology, in development since the early 1990s. However, sod seeding of annuals into perennial pasture to increase winter forage has long been practised in areas with winter dormant pastures, and techniques involving ‘roughing in’ of cereal crops into existing pastures have been in use since at least the 1960s (Badgery & Millar, 2009).
The revival of pasture cropping in Australia was led by innovative farmers Colin Seis and Darryl Cluff in the Gulgong region in the early 1990s. Seis and Cluff were frustrated with ‘conventional’ no till cropping as part of their mixed cropping and grazing enterprises because of the necessity to destroy pasture with herbicides to make way for crops, and then the need to actively re-establish pasture after each cropping phase. High input costs, and encroaching ecological issues including a rising saline water table and soil acidity pushed a re-think of their practices (Filmer & Seis, 2008). They reasoned that their native Red Grass (Bothriochloa macra) dominated pastures naturally went into dormancy in winter, and that winter growing cereals could be direct drilled into such pasture as it stopped actively growing. The exploitation of this complementary of the natural growth cycles of summer growing (C4) pasture and winter growing (C3) crops is a key insight of pasture cropping (See Fig.1).
Figure 1. Average growth rates for Redgrass (solid line) and an annual
pasture/cereal species (dashed line) at Wellington (Badgery & Millar, 2009)
Seis and Cluff’s first trials of growing oats this way were intended as an inexpensive way to fill the winter feed gap, but the oats performed so well, it was clear that decent grain crops could be produced this way (Filmer & Seis, 2008). In fact, Seis was soon achieving oat yields of 4.3 tonnes/ha (at least equalling district average yields using full ground disturbance cropping) on some areas of his property, and average yields of 3.4 tonnes/ha. The low input costs made this grain production very profitable, and the achievement of desired environmental effects of better soil health and hydrology were supported by CSIRO studies on the property (Seis, 2006; Bruce & Seis, 2005).
Pasture cropping as a land management system (and as a technique) has attracted a lot of interest over the last decade, with Seis offering consultancy both locally and in diverse agricultural areas (Seis, 2006), CSIRO studying environmental effects of pasture cropping (Bruce & Seis, 2005) and the New South Wales Department of Primary researching and promoting pasture cropping systems (Badgery & Millar, 2009).
The ‘Grain and Graze’ program ran from 2003-2008 as a co-ordinated research, development and extension project based on the collaboration of four producer levy funded Rural Industry Research and Development Corporations — the Meat and Livestock Authority, the Grains Research and Development Corporation, Land and Water Australia and Australian Wool Innovation. The program was tasked with triple bottom line based goals: “(1) Build financial capital – at least 10% more profit for mixed enterprise producers; (2) Build natural capital – better water quality and enhanced condition and diversity of plants and wildlife by producers contributing towards the achievement of catchment targets; and (3) Build social capital – increased confidence and pride among Australia’s mixed enterprise producers” (Price and Hacker 2009). Among its many initiatives and achievements, the Grain and Graze program assisted the dissemination of pasture cropping through sponsorship of research and of extension workshops, not only in NSW but in other parts of the cereal-livestock zone (Hacker et al, 2009).
Pasture cropping has also attracted strong attention from advocates of methods to increase soil carbon as a key soil health measure and as a means of atmospheric carbon sequestration. Although her findings have not been published in the mainstream literature, Dr Christine Jones has reported that testing done by the Australian Soil Carbon Accreditation Scheme she co-ordinates, shows significant soil organic carbon gains in perennial pasture based systems. Jones claims that continuous green growth and a favourable soil environment allows rapid transfer of carbon from photosynthesising plants to soil via root exudates and the vesicular arbuscular mycorrhizal symbiosis (Porteous & Smith, 2008). This angle on pasture cropping has contributed further to its dissemination, including via workshops presented by a collaboration of Jones with Colin Seis (Ham 2009).
3. Pasture cropping techniques and variations
Pasture cropping, applied as a general term referring to the planting of annual crops into a living perennial pasture, includes a wide variation of techniques around preparing for planting, timing of planting, herbicide and fertiliser types and applications, and grazing management. It includes techniques that apply herbicides prior to sowing to reduce competition from annual weeds, as well as the ‘advance sowing’ or ‘no kill’ approach, where crops are planted ‘dry’ before the autumn break with no herbicides used. The latter approach relies on the crop having more vigorous growth than germinating annual weeds (Badgery & Millar, 2009).
To prepare for cropping, Seis uses high intensity grazing to reduce pasture biomass and suppress weeds, followed by low rates of glyphosate prior to sowing, which controls annual weeds but does not harm the dormant C4 perennial pasture (Seis, 2001). Herbicide applications including the more narrow spectrum paraquat and diquat are detailed in Millar and Badgery’s research comparing pasture cropping with ‘conventional’ no till cropping and pasture-only management (Millar and Badgery 2009). At the other end of the herbicide use scale, no kill cropping uses no herbicide prior to sowing the winter crop. As outlined above, seed is sown early (‘advance sowing’) so it can compete with emerging annual weeds. In some cases, post-emergent herbicides are used to control annual weeds after no pre-sowing herbicide. The no kill technique has been taken up by organic growers who wish to use pasture cropping technology to maintain perennial groundcover, and conventional growers aiming less for grain production and more for low input, low cost winter feed. Formal research into no kill techniques to date is limited, but so far has shown poor levels of grain yield (Millar & Badgery 2010).
The sowing methods employed are also varied, but the principle is to minimise damage to the perennial pasture base while achieving good soil-seed contact. Disc seeders are successfully used in lighter soils, but where there is soil compaction, tyned implements that can rip below the seed without causing excess smearing and/or fracturing around it are necessary (Badgery & Millar, 2009).
There is also some trade off regarding the row spacing, with excessively wide spacing reducing crop yield, but excessively close spacing causing too much damage to perennial grasses. The Wellington trials, using 30cm row spacing, showed a 20% greater mortality of perennial grasses compared to undisturbed pasture, but this was compensated by additional recruitment of new seedlings (Badgery & Millar 2009). Results like this could actually improve the demographics of the perennial pasture, allowing more new growth, and more pasture diversity from the seed bank, to come through.
Fertiliser use in pasture cropping is variable, but generally low in comparison to conventional no till systems, and the use of no fertiliser at all is not uncommon in pasture cropping. In trials at Wellington, researchers found no significant difference in grain yield in pasture cropped paddocks treated with 50kg/ha vs 100kg/ha of DAP (Di-ammonium phosphate) in the dry years of 2006 and 2007 (Millar & Badgery, 2009). CSIRO researchers at Gulgong treated both pasture cropping and no till sowing with 70kg/ha of “Granuloc 12” (11.9%N:17%P:5.5%K) (Bruce et al, 2005). Badgery and Millar advise that low fertiliser rates are really a function of lower yield targets, and that the “rule of thumb” of 3kg P/tonne of grain yield target per hectare is still recommended (Badgery & Millar, 2009). However, research into nutrient cycling under different management practices indicates that available phosphorus levels in low input pasture cropping systems can be not significantly different to those found in higher input no-till cropping systems (James 2009), so lower fertiliser requirement may indeed be an inherent feature of the system due to more effective nutrient cycling.
Seis emphasises that pasture cropping is not simply a cropping technique, but is a whole farm land management system where cropping and grazing benefit each other (Seis, 2006). He stresses the importance of high density, short duration (and hence long rest) grazing or ‘pulsed grazing’ to the effectiveness of his overall pasture cropping farm system. Seis uses large mobs of sheep (about 2000) at a high stocking density (average paddock ~20ha), usually grazing paddocks for 4-6 days and resting paddocks for 70-90 days. This has resulted in increased diversity and density of native pastures, a factor that supports pasture cropping, which in turn has increased the seedling recruitment of perennials (Seis, 2001).
4. Pasture cropping and agro-ecosystem health
From its inception (or re-invention) in the early 1990s, pasture cropping has been instigated with the goals not only of lower input costs and better profitability, but also more importantly of regenerating the natural capital base, including soil conservation and health, water cycle health, and biodiversity (Filmer & Seis, 2008).
Research by CSIRO using the Seis property at Gulgong, comparing pasture cropping with conventional no till cropping and pasture only, showed a number of positive ecological results from pasture cropping. Biomass production was almost at the level of biomass in the no till system in the cropping phase, and the same as the level of production in undisturbed pasture in the pasture growing phase, meaning that total biomass production with pasture cropping over a full year was significantly greater than either of the conventional approaches. Pasture cropping produced better groundcover than a conventional cropping system, but less than the groundcover of undisturbed pasture over a year because of the disturbance at the time of sowing. Importantly, pasture cropping was also found in the Gulgong study to result in lower levels of soil water content than cropping alone (the highest water content treatment) or pasture alone, reducing the risk of water-logging and of rising saline water tables and dryland salinity (Bruce et al, 2005). Millar and Badgery’s research at Wellington found similar results regarding biomass production and groundcover for the same set of three treatments – pasture cropping, conventional no till and pasture only. It did not, however, show show significant differences in soil water content between the treatments. The different results here may have been due to a consistent lack of rain during the summer-autumn fallow period, meaning less effect of stored moisture than would otherwise be found in the conventional no till treatment (Millar & Badgery, 2009).
In the Gulgong study, the pasture cropping treatment had less variable, and on average lower, levels of available nitrogen than the conventional cropping control, indicating lowered risk of nitrate leaching and soil acidification (Bruce et al, 2005). This potential environmental plus is also associated with a yield penalty however – the lower yields associated with pasture cropping in comparison to conventional no till cropping may be largely the result of limiting N availability (Badgery et al, 2008).
James’ nutrient cycling study at Wellington indicated that low input pasture cropping paddocks had equivalent levels of available phosphorus to that in the higher input no till treatment (James, 2009). It is reasonable to postulate that this could be the result of more effective arbuscular mycorrhizal fungi activity in pasture cropping systems (James 2009), as AM fungi are documented to reduce the requirement for phosphorus fertilisers and to be inhibited by bare fallow cropping as is used in conventional no till (Gianinazzi et al, 2010).
An increase in the diversity and density of native pastures has been observed by pasture cropping practitioners, but the role of high density, short duration, long rest grazing regimes as well as the non-destructive sowing techniques is likely to play an important role in this process (Seis, 2001). A formal study of factors affecting perennial grass seedling recruitment confirmed that pasture cropping increases the rate of seedling recruitment, probably because the disturbance at sowing provides favourable micro-sites for seedling emergence (Thapa et al, 2011). The impact of pasture cropping in itself on native pasture recruitment and diversity is likely to be complex, with confounding factors such as competition from weeds and crop with C3 natives, and the potential role of nitrogen fertiliser in advantaging exotic species over natives (Millar & Badgery, 2009).
The benefits to soil organic matter of a pasture phase rotation in cropping systems is well documented (Dalal & Chan, 2001), so it is reasonable to hypothesise that pasture cropping, with ongoing retention of pasture, could give a further benefit. Studies of soil properties under different land management systems around Wellington found that pasture cropping had soil organic carbon levels higher than conventional no till cropping systems, but not as high as under continuous pasture with time controlled grazing (Warden, 2009).
A study of soil carbon under different pasture management regimes found no significant difference in soil carbon between pasture cropping and control pasture, indicating higher carbon levels than under other cropping regimes, but not confirming the hypothesis that extra green growth in winter could further increase carbon levels in comparison to grazing alone. These results were interpreted with some caution due to the short history of pasture cropping at the sampled sites and concerns regarding the inherent limitations of paired site analysis, especially the difficulty in identifying truly appropriate control sites due to different history and other factors (Chan et al, 2010).
5. Economics and risk management
A major consideration in farmers’ uptake of an unconventional approach or any significant change to farm systems will be the economic response to the change and the ability to manage associated risks. The most obvious attraction of pasture cropping in this regard is the low input costs, with not only no cultivation, but also minimal preparation prior to sowing, usually limited to a light herbicide application before sowing as opposed to multiple heavier applications to create a fallow in conventional no till cropping. Producers using pasture cropping in combination with ‘pulse grazing’ report significantly lower fertiliser requirements, further lowering input costs (Seis, 2001).
An added economic advantage is the approximately six months of extra grazing resulting from the availability of pasture in cropping paddocks right up until soon before sowing, and again very soon after grain harvest. Seis calculates that this adds a further $70-$80/ha of profit in wool production to his enterprise (Seis, 2001). Seis calculated that his best pasture cropped oat paddocks were bringing over $550/ha in profits from the grain enterprise alone, to which can be added wool production, and the removal of the need for expensive pasture re-establishment (Seis, 2006).
Comparative analysis of gross margins in pasture cropping compared to no till and to pasture only systems show pasture cropping to be more profitable than pasture only systems but not as profitable as no till cropping systems. However, no till systems showed a greater variability and increased risk compared to pasture cropping. The considerably lower input costs of pasture cropping mean that poor crop performance or crop failure is much less damaging to the bottom line than it is in the case of conventional no till cropping (Millar & Badgery, 2009).
The beauty of pasture cropping in relation to risk management is the great flexibility afforded by avoiding the need for extended preparation and fallowing, which ties producers to the cropping course of action to get yield from the prepared paddock, as pasture is destroyed. If pasture is left intact, the option not to sow a crop if conditions are unfavourable is much less damaging. In turn, if a pasture crop is sown and its performance is poor, it can simply be used for grazing with minimal or no loss – the system is already geared to grazing, and the low input costs mean a good grain yield is not needed to recoup costs. Some of this flexibility is lost with no kill cropping, as advance sowing means that seed is sown well prior to anticipated rain (Badgery & Millar, 2009). Input costs however, are a little lower again, so losses are lower if the crop performs poorly.
The Grain and Graze Whole-Farm Model was developed to help producers model the effects of different management changes, and was designed to incorporate analysis of innovative methods including pasture cropping. This model predicts favourable results with increased profitability per hectare as a result of native pasture graziers adopting pasture cropping, as well as significantly reduced losses in the event of dry conditions (Millar et al, 2009).
6. Potential for adaptation of pasture cropping systems to diverse environments
Pasture cropping has been developed in the Central West of New South Wales. There are a certain set of factors in this region that appear to make it amenable to successful pasture cropping – pastures dominated by C4 grasses whose growth patterns show winter dormancy, rain patterns that are not strongly seasonal, allowing pastures and crops to use rain as it falls, and granitic soil with relatively low water holding capacity. The system is attractive economically, especially to graziers wanting to diversify into cropping or to mixed producers finding input costs of cropping are making it too risky. There are also important environmental gains relating to soil health, reduced erosion and reduced hazard of dryland salinity (Bruce et al, 2005). Therefore there has been considerable interest in applying pasture cropping principles in other regions and other situations (Seis, 2006).
Trials at Trangie and Condobolin in the dry Western area of NSW showed good results from pasture cropping for grain and/or forage in appropriate paddock conditions. Results were poor where pastures were dominated by annual grass (Millar & Badgery 2010).
The Mid Goulburn Broken Catchment Landcare Network reported on trials of pasture cropping in North-east Victoria, an area with a much more seasonal (winter rain) rain pattern than the NSW Central West. These early trials showed a lot of the same positive results from pasture cropping, including increased pasture production and total biomass production, increased native perennial pasture and increased ground cover. In trials where crops were harvested for grain, the grain production was low, but low input costs and good feed production led to all trial participants expressing the intention to continue working pasture cropping into their land management systems. (Ham, 2009).
It is expected to be generally very difficult to get a good grain crop from pasture cropping into winter growing perennials, particularly introduced species such as phalaris and Lucerne (Seis, 2006). However, a study in North-east Victoria of pasture cropping into mature lucerne showed better biomass production and water use efficiency than that found in either lucernce or cropping alone (Harris et al, 2008). Also, some of the results of pasture cropping into pastures containing phalaris and perennial ryegrass from the Landcare trials in the same region are encouraging (Ham, 2009).
Pasture cropping trials are well under way in the Northern Agricultural Region of Western Australia, with early successes planting wheat into subtropical perennials. The Mingenew-Irwin Group research and extension association is advocating pasture cropping as a viable and sustainable option for graziers seeking improved erosion and salinity management and soil organic matter, as well as income diversification and increased fodder production. Pasture cropping is being used on sand-plain country with subtropical perennial pastures and also the bluebush (Maerina brevifolia) shrub country with heavier soil (Knight, 2010).
Pasture cropping is also being trialled in Central Queensland, with oats and wheat being planted into dense stands of American Buffel grass and Gatton Panic. There is progress being made with adapting pasture cropping principles to the challenge of a more summer dominant rain pattern with dry winters, with spring sown legumes and millet entering the system. Grain yields from winter cereals have so far been low due to lack of winter rain (Fitzroy Basin Association, 2010).
7. Pasture cropping and holistic farm system design and management
Pasture cropping as a concept and a technique is intuitively elegant – planting annual crops into perennial pasture as it becomes dormant to achieve year-round green growth. However, attempts to simply adopt it as a technique are unlikely to be successful if it is not deeply and effectively integrated with the whole farm system, especially grazing management. As Seis reminds us, pasture cropping is (or is part of) a holistic land management system (Seis, 2001). It is noteworthy that pasture cropping has attracted the attention of the permaculture community (Bradley, 2011) and the Holistic Management community (Aragona, 2010). Holistic approaches to land management such as these provide the opportunity for pasture cropping as a productive perennial agriculture to be adapted to wide range of agroecological conditions and individual producer situations.
There is potential for Keyline based landscape system design as used in permaculture design to incorporate pasture cropping as part of a water harvesting, Keyline wheeling, contour alley farming/agroforestry system. Such system design and diversification may improve environmental outcomes, particularly relating to hydrology and biodiversity, as well as productivity. A modelling study of different potential investments in land-use change for biodiversity outcomes at a regional level identified the adoption of pasture cropping with alley farming as a cost effective “system shift” to achieve ecological outcomes (Seddon et al, 2011).
The Holistic Management planning and decision-making framework, particularly its holistic approach to grazing management and biological monitoring and iterative adaptation (Savory & Butterfield 1999), has a lot to offer land managers using pasture cropping. Seis does not cite Holistic Management as providing the framework for his grazing management, but the “pulse grazing” with long rest periods based on pasture monitoring he describes (Seis, 2001) is consistent with Holistic Management principles.
Pasture cropping has made a significant contribution to sustainable land management in Australia over its approximately twenty year evolution. This farmer initiated and farmer driven system has generated a lot of interest in producers in Australia’s cereal/mixed farming zones, and its propagation has enjoyed the support of industry research and development corporations and government agencies as well as grassroots organisations such as Landcare networks. The system has been demonstrated to produce favourable environmental outcomes, including managing erosion and dryland salinity, increasing soil organic carbon and promoting agro-biodiversity including native species. Low input costs, high flexibility and reduced risk make it an economically viable system for many producers. There is much scope for further research, adaptation and integration with farming system re-design such as Keyline design and alley farming. Pasture cropping is not a panacea for sustainable grain production, as significant grain yield penalty in comparison to conventional cropping is usually experienced, and adaptation to the characteristics of some agro-ecosystems and rain patterns may not prove to be feasible. However, its principles are of global significance as land managers seek solutions to age old sustainability issues associated with annual cropping systems, and there is a lot of potential for wider adoption and further development both around Australia and overseas.
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