Lowveld Organic Services

05/10/2024

28/04/2023

Get More Bang From Your Nitrogen Buck.
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If you cut your nitrogen by 80% tomorrow, would you expect your production to drop? Of course it would… if you did nothing else. Optimising nitrogen use is one of the holy grails in a drive to produce food for a booming world population, all whilst looking after the environment.
Across the world a growing number of farmers are successfully dropping their N to astoundingly low levels in an approach that provides a wide range of benefits. How is it that some farmers can dramatically reduce nitrogen without reducing production?

The journey starts with an appreciation of soil health’s role in driving the nitrogen cycle.

Soil Structure

If you ask most fertiliser reps what the number one yield limiting factor is, they’ll probably tell you it’s nitrogen. That’s actually inaccurate; try this… hold your hand tightly over your nose and mouth for a few minutes to see what your number one factor is.

It’s air.

It is just the same for your plants and soil microbes. Without adequate airflow, roots and microbes curl up and die and natural mineral and water cycles breakdown. Compacted and waterlogged soils lose valuable nutrients including N[i], and reduce those microbes responsible for providing N to your crops.

Improving yield starts with a soil that can breathe. Air, and water, moves into soil through the gaps in soil aggregates; the crumbs formed by soil microbes. Just like constructing an apartment building, microbes and earthworms make hallways, stairwells and living spaces. Poor soil structure turns these apartments into a tarmac. This loss of structure stalls the natural nitrogen cycle.

The recent State of the Environment report shows that 78% of dairy farms were badly affected by compaction in 2013. This is a double whammy for farmers and the environment, as compacted soils require more N and lose more N into the atmosphere and waterways[ii] [iii]. Research shows, that depending on the type of N used, up to ten times more N is lost from compacted soils[iv]; requiring more inputs to maintain production.[v]

Often when considering natural nitrogen inputs, farmers most often think of legumes, particularly clover and rhizobia for N fixation. However, in healthy soils among the most common organisms are free-living bacteria which fix nitrogen into the soil. These free-living N fixers require air, so compacted soils will have less of these important organisms.

The high use of soluble nitrogen creates a vicious cycle; putting farmers on a treadmill of decreasing returns due to the breakdown of soil carbon, thus a loss of humus and an increase of microbes which love to feed on N. The loss of carbon creates the conditions for compaction, increasing runoff and erosion and limiting root growth. Just too really put the boot in, these soils then require more irrigation, creating more vulnerable farm systems.[vi]

How efficient is your N fertiliser?

Our modern farming practices are leaky and inefficient. In dairy systems only 15-35% of the N applied is actually made available to the plant, with the majority of applied N lost to the air and waterways (globally this figure is 5-15%)[vii]. There wouldn’t be many businesses happy with those kinds of inefficiencies, particularly for something which may be such a major input. So why do we tolerate it in farming?

Increasingly fertiliser companies are focusing on add-on products to improve N efficiencies, like DCD, Nitrapyrin and Agrotain. Even projections for best practices around nitrogen, the soundest estimates offer 60% efficiency at best. These products will enable fertiliser companies to continue business as usual, without addressing the key issue; why do you need to add soluble N, and why is the nitrogen cycle not working optimally?

Additional disruption to natural N function has been introduced with chemical pasture topping and herbicide brown out practices using glyphosate which has an inhibiting effect on N fixation and promotes N.

The success of Biological Agriculture begins through building a foundation to enhance natural cycles, using proactive practices which address the root causes, versus reacting to symptoms. Fostering underground livestock is an essential ingredient to reducing N inputs. One key in profitably reducing N, is through the addition of carbon based biological foods and stimulants to improve soil structure and nitrogen storage[viii] while maintaining yields [ix] [x].

Plants require nitrogen in different forms throughout the growing season; applying large volumes of N at once is ineffective in supporting plants through the year. Biological production creates significantly less emissions and leaching[xi] [xii], while providing nitrogen in plant available forms when plants need it[xiii].

Microbiology and Soluble N

Many plant species are completely dependent on microbial partners for growth and survival.[xiv] High inputs of soluble N fertilisers dramatically change microbial communities; reducing organic N and C, microbial diversity and overstimulating bacteria.

Fungi to Bacteria (F:B) ratios are important for soil structure and pasture health. New research has also shown that soils higher in fungi reduce N leaching[xv] [xvi]. Mycorrhizae, a plant symbiotic fungus, have been shown to reduce leaching by 40%.[xvii] These important fungi also produce a substance called glomalin, a relatively stable soil protein important in soil structure. [xviii] Degrading soil health and the addition of soluble N reduces the F:B ratio, creating more bacterial soils with time.

During the life and death processes which drive healthy biological systems, nitrogen goes through a variety of forms before being taken up by plant roots. Bacteria consume N and hold it in their bodies. If the soil foodweb has been compromised, through compaction or high soluble N applications, there is often lower predation from protozoa and nematodes[xix]. This means N becomes immobilised or bound in the soil, unavailable to plants.

Not all synthetic N is detrimental, adding small amounts of N (5 units/Ha) has actually been found to be beneficial for soil microbiology, acting as a catalyst to help stimulate the natural N cycle.

Research is showing that high yields can be maintained and inputs reduced through good management of soil, water, energy and biological resources. Studies have shown that the same corn yields were possible by reducing chemical inputs by half and cutting a third of costs.[xx] [xxi]

Feed your soil

Soils are an ecosystem; supporting and feeding soil microbes have huge benefits across the entire farm enterprise. Reducing nitrogen can be profitably and sensibly done through enhancing microbiology and soil health. With huge leaps forward for the environment and farming bottom lines.

REFERENCES

[i] Deurer, M., Grinev, D., Young, I., Clothier, B.E. and Müller, K. (2009). The impact of soil carbon management on soil macropore structure: a comparison of two apple orchard systems in New Zealand. European Journal of Soil Science Volume 60, Issue 6, pages 945–955

[ii] Bhandral, Rita, et al. “Transformation of nitrogen and nitrous oxide emission from grassland soils as affected by compaction.” Soil and Tillage Research 94.2 (2007): 482-492.

[iii] Lipiec, J., and W. Stepniewski. “Effects of soil compaction and tillage systems on uptake and losses of nutrients.” Soil and Tillage Research 35.1 (1995): 37-52.

[iv] Torbert, H. A., and C. W. Wood. “Effects of soil compaction and water‐filled pore space on soil microbial activity and N losses.” Communications in Soil Science & Plant Analysis 23.11-12 (1992): 1321-1331

[v] Hernández-Hernández, R. M., and D. López-Hernández. “Microbial biomass, mineral nitrogen and carbon content in savanna soil aggregates under conventional and no-tillage.” Soil Biology and Biochemistry 34.11 (2002): 1563-1570.

[vi] Khan, S. A., Mulvaney, R. L., Ellsworth, T. R., & Boast, C. W. (2007). The myth of nitrogen fertilization for soil carbon sequestration. Journal of Environmental Quality, 36(6), 1821-1832.

[vii] Gourley, C. J., Dougherty, W., Aarons, S., & Kelly, K. Improving nitrogen use efficiency: from planet to dairy paddock. www.massey.ac.nz/~flrc/workshops/14/Manuscripts/Paper_Gourley_2014.pdf

[viii] Poudel, D.D. Horwath, W.R. Mitchell J.P, & Temple, S.R. (2001) Impacts of cropping systems on soil nitrogen storage and loss. Agric. Syst., 68 (2001), pp. 253–268

[ix] Kramer, A. W., Doane, T. A., Horwath, W. R., & Kessel, C. V. (2002). Combining fertilizer and organic inputs to synchronize N supply in alternative cropping systems in California. Agriculture, ecosystems & environment, 91(1), 233-243.

[x] Aguilera, E., Lassaletta, L., Sanz-Cobena, A., Garnier, J., & Vallejo, A. (2013). The potential of organic fertilizers and water management to reduce N2O emissions in Mediterranean climate cropping systems. A review. Agriculture, Ecosystems & Environment, 164, 32-52.

[xi] Oquist, K. A., J. S. Strock, and D. J. Mulla. “Influence of alternative and conventional farming practices on subsurface drainage and water quality.” Journal of Environmental Quality 36.4 (2007): 1194-1204.

[xii] Magesan, G. G., & McFadden, G. (2012). Nutrient leaching under conventional and biological dairy farming systems. Advanced Nutrient Management: Gains from the Past-Goals for the Future. (Eds LD Currie and C L. Christensen). http://flrc. massey. ac. nz/publications. html. Occasional Report, (25).

[xiii] Burger, M., & Jackson, L. E. (2003). Microbial immobilization of ammonium and nitrate in relation to ammonification and nitrification rates in organic and conventional cropping systems. Soil Biology and Biochemistry, 35(1), 29-36.

[xiv] Van Der Heijden, Marcel GA, Richard D. Bardgett, and Nico M. Van Straalen. “The unseen majority: soil microbes as drivers of plant diversity and productivity in terrestrial ecosystems.” Ecology letters 11.3 (2008): 296-310.

[xv] De Vries, F. T., Hoffland, E., van Eekeren, N., Brussaard, L., & Bloem, J. (2006). Fungal/bacterial ratios in grasslands with contrasting nitrogen management. Soil Biology and Biochemistry, 38(8), 2092-2103

[xvi] De Vries, F. T., Liiri, M. E., Bjørnlund, L., Bowker, M. A., Christensen, S., Setälä, H. M., & Bardgett, R. D. (2012). Land use alters the resistance and resilience of soil food webs to drought. Nature Climate Change, 2(4), 276-280

[xvii] Asghari HR, Cavagnaro TR (2012) Arbuscular mycorrhizas reduce nitrogen loss via leaching. PLoS ONE 7, e29825

[xviii] Rillig, M. C., Ramsey, P. W., Morris, S., & Paul, E. A. (2003). Glomalin, an arbuscular-mycorrhizal fungal soil protein, responds to land-use change. Plant and Soil, 253(2), 293-299.

[xix] Griffiths, B. S. (1994). Microbial-feeding nematodes and protozoa in soil: Their effects on microbial activity and nitrogen mineralization in decomposition hotspots and the rhizosphere. Plant and Soil, 164(1), 25-33.

[xx] Pimentel, D., Culliney, T. W., Buttler, I. W., Reinemann, D. J., & Beckman, K. B. (1989). Low-input sustainable agriculture using ecological management practices. Agriculture, ecosystems & environment, 27(1), 3-24.

[xxi] Chivenge, Pauline, Bernard Vanlauwe, and Johan Six. “Does the combined application of organic and mineral nutrient sources influence maize productivity? A meta-analysis.” Plant and Soil 342.1-2 (2011): 1-30.

18/04/2023

Tortricidae moth control: What is happening and why is mating disruption no longer working?
Dr Schalk Schoeman - SAMAC
Moth borers are problematic due to the complexity of their life cycles and their ability to adapt to a changing environment. Mating disruption is a very good environmentally friendly method of managing these pests but during the last three years erratic performance has been reported from the field.
Possible reasons for mating disruption failures
Insects adapting and evolving to overcome the mating disruption effect.
This is very rare but have occurred in Japan after about 14 years of nearly continuous usage of mating disruption to combat the tea tortrix Adoxophyes honmai. Mating disruption products have been widely used in Subtropical regions of South Africa, providing a constant selection pressure for resistance. However, there is currently no local evidence proving or disproving this phenomenon.
Influence of adjoining host plants
Moths from the insect family Tortricidae are ideal candidates for mating disruption and most of them are very polyphagous. This was demonstrated in Barberton where macadamia orchards bordered sugar cane plantations and in Nelspruit with avocado orchards near sugar cane. Although sugar cane is a recognised host for the false codling moth no information regarding the macadamia nut borer is available. Yellow Delta traps baited with pheromones of both species were deployed deep inside the sugar cane plantations and moths of both species were readily captured.
In this situation there was nothing (not even the deployment of mating disruption dispensers along orchard perimeters) preventing gravid female moths from migrating into the surrounding macadamia orchards. The effect of immigration was also clearly demonstrated this season in the Nelspruit region where definitive edge effects were observed in a mature cv. 344 orchard that was surrounded by dense subtropical forest which presumably contained several wild host plants.
KwaZulu/Natal is one of the fastest growing macadamia production regions and most of these developments occur near sugar cane plantations. It is expected that once these orchards reached maturity more damage from this group of pests can be expected.
Small or fragmented orchards and orchard shape
It is important to realize that the essence of mating disruption is to saturate the air inside an orchard with female pheromones. This will eliminate pheromone gradients used by males to locate females. If the orchards are too small (minimum size – 8ha) or if the orchards are long and narrow or if the orchards are regularly subjected to wind (such as in coastal areas) poor performance of mating disruption can be expected.
Influence of environmental conditions
Very high or very low temperatures, excessive rainfall or wind may temporarily disrupt the artificial pheromone blanket generated by the emitters in the orchards. This will allow males to find females, mate, and subsequently lay eggs. A breach of only a few days may be all that is necessary and could rapidly give rise to a new generation in the nuts especially when one considers that maximum oviposition of these moths usually occurs ± 2 days after pupal emergence.
Lack of knowledge regarding relative species abundance of individual species.
Mating disruption hinges on s*x pheromones which are species specific. The in-depth study by Enslin (2023) clearly points towards a more complex picture of seasonal succession by a range of species. This study is supported by findings of an earlier study which already took place during 2002.
Conclusion
Mating disruption is an internationally recognised method of controlling Lepidopterous pests (Especially from the insect family Tortricidae). In other production systems this assumption appears to be still valid, but it really is evident that there may be problems in macadamia production systems. Only two reasons make logical sense namely:
1) Individuals of the macadamia nut borer complex may have evolved around the mating disruption process and may now successfully locate females even if mating disruption dispensers are deployed.
2) Macadamias may be affected by a complex of moth species throughout the season, rather than just one specie. Using a single pheromone in this this scenario will be ineffective.

03/04/2023

We can build your pumpstation in our factory, and deliver it to the site.

09/03/2023

09/03/2023

Lessons learned from the management of the red scale in citrus: Can we use the same principles to manage the macadamia felted coccid.
Dr Schalk Schoeman (SAMAC)
Red scale is one of the most notorious citrus pests globally and severe infestations will lead to leaf senescence as well as branch dieback. Interestingly a yellow halo on infested leaves will also develop around feeding female red scales which is similar to the felted coccid (Fig,1).
Being scale-like, the macadamia felted coccid broadly has a life cycle which is comparative to that of the red scale but there are also important differences one must consider. Damage potential of the macadamia felted coccid is possibly more severe as large upper sections of the trees may die due to the feeding activity of these insects. The red scale secretes honeydew which attracts ants that will interfere with biological control while the macadamia felted coccid does not secrete this sugar rich substance.
What implication does all this now hold for control of the macadamia felted coccid?
Firstly, the felted coccid was introduced to South Africa without its natural enemies. This has led to rapid increases in pest numbers. Fortunately, the global academic community is very small and an ex South African researcher working on biological control of the coccid in Hawaii was contacted. The USDA was subsequently consulted, and they agreed to provide the parasitoid Metaphycus macadamiae to South Africa. This saved the South African macadamia growers a significant amount of time and money as in similar cases, a researcher normally must be sent to the country of origin of the target pest (Australia) to search for and select suitable parasitoids.
Will this parasitoid be the silver bullet that will control the felted coccid?
The answer is both yes and no and for clarity we will have to refer once again to the citrus management strategy. In citrus the red scale was brough under relatively good levels of biological control by various natural enemies (local and imported) but pesticides used against thrips that is regarded as the key pest upset the biological balance. Various synthetic pyrethroids and organophosphates used for thrip management were regarded by early field entomologists as incompatible with an Integrated Pest Management (IPM) programme. The situation in macadamias is very similar as the same products are widely used for the control of stink bugs which are regarded as key pests of this crop.
This observation points that the key for successful sustainable coccid control is the importation, release, and successful establishment of the coccid parasitoid but that this practice hinges on the sustainable management of stink bugs. The importance of this is underlined by the observation that the coccid may become a problem in its country-of-origin (Australia) when broad spectrum products are too frequently used.
In citrus, levels of biological control can be considerably elevated by ant control. Ants are lured to honeydew secreted by the red scale and in so doing they protect the scales from parasitoids. This is unfortunately not an option for macadamias because the felted coccid does not secrete honeydew.
The usage of various grades of mineral oils, sprayed during the cooler winter months should also be regarded as a very IPM compatible control option. This practice hinges on effective spray deposition and for that pruning is essential.

22/02/2023

13/02/2023

Mealybugs – a deadly menace or a lame duck?
Dr Schalk Schoeman - SAMAC
Mealybugs have become an unfortunate reality in many orchards. The questions always asked are: Since they do not cause direct damage to the kernels is it important to control these insects and what damage do, they actually cause? The following section should hopefully shed some light on this subject.
Background
Macadamias are generally affected by the Karoo thorn mealybug (Nipaecoccus viridis) as well as the long-tailed mealybug (Pseudococcus longispinus). The latter insect can be identified by the presence of four extra-long filaments posteriorly while a useful feature to identify the former insect, is the ability to draw the wax covering in long filaments (up to 150mm). Both insects are luxury consumers and ingest more plant sap than they can use. The excess is excreted as a sticky sugary solution (honeydew). Interestingly, one theory suggests that manna used by the Israelites in the Bible may be honeydew secreted by a sap sucking insect occurring in Tamarisk trees. This nutrient rich secretion is often overgrown by a black fungus (sooty mould) (Fig.1)
Where do mealybugs come from?
These are indigenous insects that are usually under very effective biological control and their presence is normally a good indicator that the biological balance is probably compromised in some way. Overapplication of broad-spectrum pesticides is the most obvious culprit but any production factor that compromise the effects of natural enemies could possibly be blamed. In this regard it was observed that dense unsprayed orchards could also harbour sizable populations of mealybugs.
Mealybugs are also attracted to plants with high nitrogen levels and concomitant soft growth.
What damage do they cause?
High numbers of these pests debilitate the plant by sucking large volumes of plant sap and may even interfere with stomatal functioning. On severely infested farms, populations of these insects caused premature desiccation and abortion of the nuts (Fig.1). This must be regarded as exceptional and normally do not occur on most farms.
Feeding by these insects my lead to rosetting of growing tips which may hamper spray pe*******on for this and other insects.
Because these insects feed on plant sap they may be important vectors of plant diseases
The ubiquitous black fungus, sooty mould may hamper photosynthesis and the combined effect of feeding by many individuals may compromise the immune systems of affected plants, rendering them more susceptible to pathogens such as Botryosphaeria or even insects such as shot hole and ambrosia beetles.
Management
If a strict spraying regimen consisting of broad-spectrum products was the initial cause of the problem, the first logical course of action would be to analyse spray records intensely and adapt the original spraying program by using softer products with a proven track record of efficacy.
In most cases biological control will take over when the spray frequency of broad spectrum products is reduced. In severe cases chemical intervention may be necessary (refer to the registered product list for macadamias in South Africa). Included in this list is an insect pathogen that could also be applied as a form of biological control.
These insects are often prevalent in the crotches of the main branches or other inaccessible areas such as cracks or under loose or peeling bark. Effective pruning that will improve spray recovery on these target areas may therefore be a very good departure point for sustainable mealybug management.
A range of natural enemies such Anagyrussp. and Cryptolaemus montrouzieri are commercially available and the release of these organisms should always be considered before chemical control is attempted.

14/01/2023

09/12/2022

Small scale Farmers, successfully farming with Floppy Sprinkler.

08/12/2022

SAMAC Information Session on the Macadamia Felted Coccid (MFC) held on 17 Nov 2022 (10h00) at Braemar Farms, Arch & Arrow Venue, White River.
Feedback session regarding the macadamia felted coccid
Dr Schalk Schoeman - SAMAC
The macadamia felted coccid is a scale like insect that was detected on macadamia orchards in the Barberton Valley during 2017. The insect was subsequently accidentally spread to isolated localities Nelspruit/White River and the North coast areas of KZN with infested plant material. From these areas the pest spread on its own to various secondary sites and is now regarded as nearly fully established in the Nelspruit/Barberton/White River areas. Dangers posed by the insect include:
1) Dieback of large portions of the trees with concomitant production losses
2) Predisposition of the trees to bark and ambrosia beetles as well as the fungus responsible for branch and tree dieback
3) Additional costs of pesticides and diesel associated with high volume applications of pesticides on main trunks as well as scaffolding branches.
4) Stink bug sprays are normally applied at considerably lower rates and when these sprays are applied on tall and dense mature macadamia trees, it is expected that chemical gradients will be formed. These gradients are bound to manifest in the rapid build-up of resistance if the situation is allowed for long periods of time
Dr Schalk Schoeman from SAMAC gave a talk on the current situation regarding the pest as well as progress of research. A macadamia steering committee was recently formed to ensure that research is tackled as speedily and as effective as possible. The following projects were identified
1) Importation of a parasitic wasp (Metaphycus macadamiae) from Australia via Hawaii. For permission to release this exotic insect in our environment, it will now have to be stringently tested. Fortunately, South Africa has a very good name in this regard internationally but depending on results, this project may require up to 5 years to conclude.
2) South Africa is a very biodiverse country and all indigenous mortality causing agents must be quantified. This includes parasitic insects as well as microbial disease-causing organisms. Together with this, commercially available microbial products will be evaluated for management.
3) Chemical control is usually the first line of defence in cases like this but there is currently no pesticide registered against this insect. DALRRD was also engaged during the first meeting of the steering committee with the aim of expediting emergence pesticide registrations.
4) The mfc was unknowingly spread via infested plant material and nursery standards and protocols will be critical in preventing further spread of this pest into hitherto uninfested areas.
The feedback session was concluded with a pesticide applicator demonstration from Avima as well as a question-and-answer session regarding the dispersal potential of this pest. The ability of insects to disperse into an open niche is often astounding and it was no different with the mfc. Service providers to the farming community were urged to be careful and to visit uninfested farms first during their daily rounds. The event was well attended with just more than 100 people showing up and was concluded with a braai overlooking the lovely dam.