If I was starting a career in agriculture today, Australia is the place I would go to prepare for it.

Why?

One good reason is Richard Stirzaker, author of Out of the Scientist’s Garden: A Story of Water and Food (CSIRO Publishing, 2010, 193 pp.). Expert gardener, tinkerer, educator, raconteur and, Senior Research Fellow at the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Canberra, Australia, Stirzaker melds the rigor of scientific thinking with a profound understanding of scale and problem solving as it affects how we feed ourselves. Stirzaker invites us to ponder the meaning of hard-to-pin-down words like “sustainable” that have ambushed the lexicon of agricultural scientists and emissaries of development (now pivoting to “climate smart®”). What does a template for sustainable agriculture look like in a world expected to reach a human population of 9+ billion by 2050?

Today, irrigation accounts for more than 70% of groundwater diversions annually, and for more than 90% of total consumptive water use including surface water (FAO 2010; Siebert et al. 2010). As Stirzaker notes, there is plenty of water on planet Earth, but 97% is salt-laden ocean water. However, if we try irrigating with saltwater, plants will wilt and eventually die. Less than 3% of water is fresh enough for watering plants, and two-thirds of this is locked up in icy blocks. The sustainability of our global food system is inextricably linked to the remaining 1% supply of freshwater. We can argue the merits of fertilizing with organic nutrients in compost over that of soluble inorganic fertilizer, i.e. the insufferable and counter-productive “natural” vs. “synthetic” debate. In all cases, essential nutrients must be dissolved in water and available at the plant root; and, there must be enough water in the soil to sweep nutrients to the exchange sites on roots if we are to sustain, let alone increase, the food supply. The problem of water supply is the most urgent one facing the global food system, and Stirzaker is acutely aware of this. Throughout, the author emphasizes the fundamental soil-plant-water relationships underpinning the agronomic sciences with a minimum of jargon and, explains how intervention in the food system can flounder despite the scientific merit of an idea.

The book is divided into three parts. Each part has seven chapters in essay form, loosely turning on a theme. Part 1 “The View From Our Garden” traces Stirzaker’s professional roots back to the family garden of his youth. He opens with this simple premise: “This is not a book about gardening. Yet the story of feeding the world begins in a garden”. The massive, unending streams of global energy, water, and fertilizer needed to keep the world fed are difficult for anyone to comprehend. But the garden, Stirzaker contends, is a scale we can comprehend. As a food production system, the home garden is relatively simple. The consequences of crop failure are usually not catastrophic for the gardener. One can tinker infinitely without the fear of going hungry or losing one’s shirt. The garden is also an excellent place to learn how plants interact with their environment. Plants respond to temperature, frost, day length, humidity, and moisture in different ways. Once we understand, for example, how onion varieties respond to day length or cabbage and broccoli to temperature, we can take advantage of this knowledge to maximize the variety, quality, and supply of food produced from the garden. The commercial grower exploits the same fundamental knowledge, only on a larger scale.

Part 1 also delivers the mea culpa agricola “The Lapsed Organic Gardener”. Early on, Stirzaker was an avid reader of gardening books. A particular favorite was The Complete Book of Self-Sufficiency by John Seymour. I never read Seymour’s epistle, but there were many books like this published in the 1970s mostly written with urban exiles and suburban homesteaders in mind. I, too, had teenage dirt hog idols like Louis Bromfield, author of Pleasant Valley (1943), Malabar Farm (1945), and Out of the Earth (1948). Bromfield’s literary star had long since faded by the 1970s and with it, his prolific writings, mainly surviving as obsolete, forgotten tomes moldering on the shelves of the public library where I first discovered them. Bromfield was not a practitioner of organic agriculture but adapted some concepts to his Ohio farm operation. Early on, he abandoned the idea of the generalized self-sufficient farm, to specializing in livestock and dairy. The pattern of the specialist farm has intensified in the post-WW II era, with little hint of changing direction. This is one of the irresistible forces driving contemporary food systems, Stirzaker concedes. The eco-friendly gardening methods described in books like Seymour’s are ill-suited to commercial-scale production. Still, one idea from the Malabar Farm sagas that continues to resonate with me is the potent but generally neglected influence of the subsoil in agriculture. Despite poor topsoil inherited from years of bad plowing, Bromfield was convinced that his glacial Ohio soils were fertile, advocating “farming from three to twenty feet down”. There, locked away in the rich subterranean fabric are stocks of water, nutrients, and trace minerals awaiting discovery by plant roots. His recipe for restoring worn-out land emphasized deep-rooted legumes like alfalfa.

Image 1. Louis Bromfield (1896-1956), Ohio-born American novelist and pioneer of conservation farming in the 1940s. Bromfield's recipe for restoring worn-out land emphasized deep-rooted legumes and grasses. Largely forgotten by the 1970s, the chronicles of Malabar Farm and Malabar-do-Brasil aroused my interest in food and energy systems, soil, and tillage.

Stirzaker built on the same idea decades later, mixing shallow-rooted vegetable crops with strips of alfalfa (aka “lucerne” in Australia). In this system, the deep-rooted alfalfa picks up nutrients that filter past the vegetables, pulling them back to the surface. Cuttings of alfalfa are then placed in the vegetable rows where they decompose, releasing the dodgy nutrients. The difference is, Bromfield’s alfalfa monoculture scaled commercially, whereas Stirzaker’s vegetable-alfalfa system did not.

This brings us to the subject of “agroecology”. Nowadays there is a great deal of buzz about agroecology, at least within academic circles. Agroecology emphasizes biological complexity like Stirzaker’s vegetable-alfalfa system. On a non-mechanized artisan level, mixed cropping systems may be successful but it is difficult to implement them on a commercial scale. Agricultural mechanization requires a degree of simplification to implement. In reality, a sustainable food system has many interlocking facets that impart buoyancy to the whole. Foremost is creating a soil environment where roots are unhindered by compaction, pH, and the supply of mineral salts and water. This depends on direct human intervention, not biological complexity.

Sustainable soil and water management should invoke a modus operandi that is adaptive and free of taboos provided it builds productivity, quality, and income following proven methods of land husbandry. The idea that there is one path leading to sustainability, whether fixed in the organic canon, biodynamics, net zero, permaculture, or what have you, is a conceit advanced mainly by those who do not comprehend the complex, interlocking infrastructure that has evolved to feed an urban, industrialized world. Agriculture isn’t natural, and leaving things for nature to balance out ensures that a large part of what we produce will be devoured by hungry competitors. This doesn’t mean, Stirzaker stresses, that we shouldn’t strive for better ecological outcomes to buttress the global food system. The challenge ahead is reducing agriculture’s ecological footprint as it becomes more productive, which it must. On the other hand, we must accept that there are stark efficiency constraints in commercial farming operations. As spectators, we’re not free to foist our cherished ideas on those who produce the food we eat.

Part 2, “A Journey Through Soil” gets down to the business of soil water, water supply, and irrigation; why, as Stirzaker asserts, it is so difficult to know how much water there is in the soil, and, why irrigation is often so inefficient or damaging to plants. As a veteran of the irrigation business, much of what Stirzaker says rings true. Chapter 10, “The Machingalana is Talking to Me” relates the author’s approach to solving a particularly thorny problem for the irrigator: measuring how much water is in the soil in a simple, straightforward way. Stirzaker’s answer is the FullStop wetting front detector, a simple mechanical device designed to detect the depth that water infiltrates in the soil. For now, I pass on the wetting front detector and related chapters because they deserve a separate blog which I must postpone for later.

Here, I want to focus attention on chapter 8, “The Tale of Clever Clover”. The clover in this tale is subterranean clover (Trifolium subterraneum), or sub clover for short. Clovers are legume plants. This means that they can self-produce nitrogen fertilizer, literally out of “thin air” (Earth’s atmosphere consists of about 78% nitrogen). A soil-dwelling bacterium called Rhizobium colonizes the roots of legumes, forming small nodules where they live. The bacteria come equipped with special enzymes needed to convert atmospheric nitrogen, which plants can’t use, to ammonium nitrogen which plants can use for protein synthesis. The bacteria fix the nitrogen and pass it on to the clover plant. In exchange, the bacteria get energy in the form of sugars from the clover (clover still needs potash, phosphorus, and lime so it’s no free lunch). The name “clever” clover presumably derives from this clever act of nature, or so it appeared to the science journalist who interviewed Stirzaker. The tale begins with an extra garden bed Stirzaker had seeded with sub clover. After blooming, the annual clover dies off naturally, leaving behind a nitrogen-rich organic mulch. Beneath this decaying mulch, Stirzaker found revitilized soil: soft, crumbly, aromatic. Eureka! At last, the Rosetta stone of no-tillage organic crop production was revealed, springing from beneath the remains of a humble clover plant. What followed is an avalanche of media attention directed at the Clever Clover plots and the man behind their discovery. Clever Clover kits were quickly assembled and sold like hotcakes. It must have been a classic light-bulb-goes-off moment like announcing you’ve just discovered DNA or something equally game-changing!

It was not to be. While Clever Clover was a big hit with home gardeners, it did not influence commercial vegetable production in Australia or elsewhere. As Stirzaker explains, innovations that solve one set of problems often create new ones, and scale matters. Planting systems designed for the garden may be eco-friendly innovations, but it is difficult to implement them on a commercial scale. New risks are introduced to the system, and farmers do not like taking risks with their livelihoods. Problems like: What happens if the clover gets infested with weeds or slugs? (Cutworms, wireworms, and rootworms are the under-mulch nemesis in North America). How do you plant and irrigate through the mulch, and what happens to the mulch after harvest? All were unknowns, and Clever Clover did not supply the answers.

The Clever Clover tale parallels a similar epiphany when I thought I had discovered, by accident, something game-changing, only to find that it, too, didn’t prove up under testing. This tale involves rye, a grass, but could apply equally to legumes like sub clover. Between 1999 and 2003 we were running subsoil nitrogen recovery studies on small grains. The aboveground plant biomass: grain, leaves, and stems, were cut in April and May, except for the “check” plots (these are control plots in agricultural field experiments). The checks were left alone: harvest, no clean cutting. In turn, the rye and other small grains went to seed. The rye, in particular, had grown very tall because we had planted corn on that land the previous year, and some of the nitrogen fertilizer that was applied to the corn crop carried over to the rye. The unharvested, uncut rye slumped over from the weight of its top-heavy growth (known as “lodging”), forming a perched canopy. Beneath this canopy, no weeds had germinated. In contrast, the plots that had been clean cut were covered with them.

Image 2. Small grain plots on the Thompson Farm, site of my Clever Clover epiphany. The green strip in middle is where grain was cut earlier, now flush with weeds. Compare to the weed-free under-canopy (inset) photo taken in mid-June in the unharvested plots (the greenish crust is moss growing on the soil surface). I thought we could duplicate the same weed-free effect in row crops with the mechanical roller-crimper, reducing the need for costly herbicides while advancing broader environmental goals such as reduced soil erosion and improved water quality. It didn't work out that way.

It is well known that rye releases toxic phytochemicals during decomposition that inhibit the germination of small seeds, a phenomenon known as allelopathy. What happens to those chemicals after the rye has been terminated is not well understood, but it is presumed they leach into the soil where they are broken down by microorganisms. Given the right conditions, I reasoned that duplicating this weed-free effect might be possible in annual row crops. Eventually, the mulch would decompose into a soft, spongy, organic mold, earthworms would improve aeration and recycle nutrients with their castings, and the soil would be conserved, all in one nifty package. This was my Clever Clover moment. I thought the conundrum of herbicide-free no-tillage could be solved with enough mulch. At the same time, reports of mechanical roller-crimper tools began to circulate in the agricultural world. Brazilian farmers were using the roller-crimper to non-destructively terminate standing cover crops, and prototypes soon appeared in North America. It wasn’t long before I got my hands on one of these tools. Field trials were initiated in soybean and cotton comparing high-density rye cover crop mulch with and without herbicide treatment. Turns out, as herbicide applications were reduced, weed populations increased in spite of the pressed mulch, and soybean and cotton yields declined in lockstep. Not unsurprisingly, the worst plots were the no-herbicide plots, some of which looked like triple-canopy jungle by the end of the season (summaries of this pioneering work are available here and here).

Image 3. Cover crop roller machine. Cover cropping adds a layer of complexity to the food system. For example, if termination of cover crop growth isn't timely, critical supplies of soil moisture can be rapidly exhausted, increasing the risk of drought stress for the subsequent summer cash crop. Richard Stirzaker underlined the necessity of understanding the consequences of our interventions in the food system. Sustainability has many facets, and future events may change the way we interpret it.

What happened? We were not able to deliberately reproduce the same effect observed in the small grain plots. The physical barrier created by the flattened rye residue, coupled with leaching phytochemicals, ultimately proved insufficient to keep weeds from germinating. The slightest gap in the mulch was enough to give tiny weed seedlings purchase. Worse yet, some of the weeds that gained a foothold were noxious perennials like horseweed, dog fennel, and pokeweed that would return year after year, with no reliable means of mechanical control. This was my Clever Clover moment. I understand just how Richard Stirzaker must have felt after realizing that it was all much more complicated; there’s no easy recipe for eco-friendly agriculture. In the following months we pitched the idea of rolling cover crops to the corn, soybean, and cotton commodity groups of North Carolina because we needed money to continue evaluating the roller-crimper tool. There were no takers. Producers were well aware of the cover crop roller and made it clear they had no interest in it. The project ended, and we moved on. I beleive there are still a few cover crop rollers in operation in North Carolina. But overall, mechanical roller-crimper has not influenced row cropping in North Carolina, or anywhere else in North America, for the same reasons that Clever Clover was unsuccessful.

The Clever Clover tale points up two enduring lessons as Richard Stirzaker tells it: (1) it is not easy to intervene in the food production system; and (2) there’s a big difference between having an impact and having an influence. “Impact” is something that rivets attention over a short period, i.e. the proverbial “flash in the pan” or “fifteen minutes of fame” syndrome all too common nowadays, especially for projects with short investment turnabouts. Having an influence takes a lot of persistent, painstaking effort over a long time horizon because it involves fundamental changes in the way people do things. When we tinker with agricultural systems, the full effect of our intervention is often obscured by short-term objectives. I suspected that establishment effects were hindering the efficacy of the cover crop roller. Longer-term studies would be needed to calibrate the system, including a transitional phase where the surficial weed seed bank could be exhausted through a combination of cover cropping and prescription herbicide treatment. This work never materialized.

To Stirzaker’s list, I would add a third lesson: It is not easy to discover something new. Farmers have been tinkering with clover and cover cropping for many decades. Few of these experiments have garnered the media attention of Clever Clover, but their stories nonetheless have been circulated in newspapers, agriculture journals, and magazines. In fact, the Clever Clover idea had been tested before Richard Stirzaker’s shadow graced the land down under. But who knows? Maybe someday, in a world very different from that of today, we’ll revisit the Clever Clover innovators like Stirzaker and others for guidance.

Image 4. Fall cabbages planted in pearl millet (Pennisetum glaucum) mulch after flattening with the cover crop roller. Cool-season crops like cabbage and broccoli were a better fit for no-till cover crop systems because the cooler temperatures in fall curbed warm-season weeds, leaving emergent winter annuals the only competition.

Part 3, “Feeding Ourselves” examines the global food production system, paying attention to the balance of productivity and ecological footprint. Tillage is a big part of that picture, and Stirzaker devotes a chapter to how our concept of land husbandry has changed over time. Should one double-dig the garden beds or no-till them? How does tillage affect the infiltration of water into the soil? Does soil structure matter? Is permaculture the answer? How are we to educate the next generation of agricultural scientists? Stirzaker explores these and other topics, each arising from questions about what we eat, how we use water, and how to think about agricultural efficiency in a realm of competing interests.

Out of the Scientist’s Garden is not a “how-to” manual. It will not teach you to make compost or become self-sufficient. There are no recipes for sustainable agriculture; no answers to humanity’s pressing need for ever more food, housing, and energy. It’s about “how to think about things”, using water as a didactic prop. Stirzaker’s hope is that readers will bear witness to their own experiences, perhaps reaching different conclusions.

I strongly recommend this book to anyone interested in agriculture, water, sustainability, and the natural resources. If you’ve been around the block a few times like me, eaten dust, indulged the worldly oracles, and taken the measure of all the moods of human wisdom and folly, there’s bound to be something here that parallels your turn in the arena.

Further Diggings

FAO, 2010. AQUASTAT-FAO’s Global Information System on Water and Agriculture. Available at https://www.fao.org/aquastat/en/. FAO, Rome, Italy.

Siebert, S., J. Burke, J.M. Faures, K. Frenken, J. Hoogeveen, P. Döll, and F.T. Portmann. 2010. Groundwater use for irrigation-a global inventory. Hydrol. Earth Syst. Sci. 14(10): 1863-1880. Available at https://hess.copernicus.org/articles/14/1863/2010/ (last access: 16 March 2013).

Text slightly edited from the original for clarity and links re-verified by the author 01 August 2026.