Fundamentals of Nutrient Management: Why Nutrient Replacement is Essential in Organic and all Agriculture

There is a belief, going back to the foundation of organic agriculture, that nutrient replacement, i.e., the use of ‘fertilisers’, within organic agriculture is not required. Scientific theories and laws as well as practical farming evidence, now conclusively shows that this belief is incorrect, and nutrient replacement / cycling is essential for all forms of agriculture including organic. This paper is an explanation of why nutrient replacement / cycling is essential, starting at the most fundamental levels of the physical laws of nature, progressively building a holistic / systems based view of the behaviour of nutrients, and also energy, in farm systems and the biosphere as a whole. While such a view may at first appear overly detailed, even irrelevant to agriculture, one of the primary keys to the success of scientific understanding is the ability to create a theoretical understanding with precise predictive power. Much of agriculture is based in the complex sciences of biology and ecology where random processes prevent theoretical explanation and prediction i.e., much of agricultural science is empirical. Nutrient management is one of the few areas of agriculture where fundamental physics, even at the sub-atomic level, can penetrate right through the noise of biological systems to directly inform the actions of farmers. Empowered by such understanding farmers have the ability to fully understand the fundamentals of nutrient management and make better informed decisions about their own practices. Such a holistic perspective also ‘shines a light’ on the unsustainability of nutrient management in ‘industrial’ agriculture and the wider human societies of which it is the foundation, as well as reiterating the solutions that have been known for two centuries

Overview of organic agriculture

The acquisition of food, textiles and other resources from plants and animals has been a major concern for human societies, from the earliest days as hunter-gathers, through pastoral and swidden phases, to agrarian societies, with an associated trend away from nomadic to sedentary lifestyles. Yet as agricultural production intensified and expanded, the negative effects on the underlying resource base have also increased. The history of environmental damage caused by agriculture is well documented; impacts include air pollution from greenhouse gases such as carbon dioxide, methane, nitrous oxide; land degradation as a result of clearing, cultivation of sloping land and salinity; water pollution from fertilisers, pesticides, overuse and wetland draining; and the loss of biological and ecological diversity (Norse and Tschirley 2003). In the area of conventional weed science, for example, considerable attention has been placed on herbicides but this has not achieved a long-term decline in agricultural weed populations. Instead, farmers have become dependant on herbicides as widespread resistance in a range of weed species has emerged (Gill 2002)

Results from the arable crop rotation study at Oak Park 2000 - 2007

An organic rotation trial was established at Oak Park in 2000. The crop sequence in the seven year rotation was: two years grass-clover, winter wheat, potatoes, winter oats, lupins and spring barley. The grass-clover, which supplies nitrogen to the system, also provides vegetation which of late is cut and mixed with cereal straw to produce compost. The compost replaced sheep manure which was available up to 2007. Manure was applied to potato plots prior to cultivation for the period 2002 to 2007 and to barley plots from 2005 to 2007. The average yield of crops over the period of the rotation was: winter wheat 5.9 t/ha, potatoes 32.7 t/ha, winter oats 5.8 t/ha, lupins 2.4 t/ha and spring barley 4.5 t/ha. Triticale, which was grown in one of the plots designated for winter wheat, had an average yield of 7.5 t/ha. Lupins have been unsatisfactory due to uncompetitiveness with weeds and lateness of maturity

Organic Weed Management: A Practical Guide

This technical guide provides an overview of strategies to manage weeds in organic productions such as crop rotation, soil management, crop management, and weeding machinery. The tool provides weed management recommendations for both annual and perennial crops. The guide is designed specifically for organic farmers providing an overview of weed management methods

Organic Stockless Arable Rotation Experiment 199-2007: Review and Analysis Report (Teagasc).

• In 2000 an organic rotation research and demonstration experiment was set up at Teagasc (Irish Agriculture and Food Development Authority) Oak Park, Co. Carlow, with an overall aim ‘to improve the yield and quality of organic arable crops in Ireland’ • A field scale, long term, stockless seven year rotation experiment was established having three replicates. The single rotation consisted of two years grass / clover pasture followed by five years of cropping, three in cereals, one potato and one legume crop. • The area was previously in long term silage pasture, which provided a good base from which to convert to organic. • Within and across the plots a range of ‘component research’ was undertaken, mainly cultivar comparison and some sowing rate experiments. • The component research varied and is regarded as being at variance with the long term monitoring of the rotation. • The experiment would benefit from a re-confirmation of its aims, objectives, experimental design and management. • Considerable value is placed on the instigation of an ‘industry’ consultative group consisting primarily of organic farmers as well as members of the organic movement, and other agricultural representatives. • It is recommended that the experiment continues to be un-certified, as certification is solely a marketing tool which is often at odds with the requirements of research, especially where standards are at odds with organic principles. It is suggested that a stakeholder representative group would give the experiment the credibility that farmers obtain from certification, i.e., it would be peer reviewed by leading organic farmers

The effect of seed moisture content and the duration and temperature of hot water treatment on carrot seed viability and the control of Alternaria Radicina

Hot water treatment of seeds to control seedborne pathogens is an important tool for organic seed production. Reducing seed moisture content may have the potential to increase carrot (Daucus carota L. var. sativus D.C.) seed tolerance to treatment. Two hot water seed treatment experiments were conducted. The first studied the effect of seed moisture content (SMC), treatment temperature and treatment duration on germination. Maximum safe treatment temperature and durations were established at 50°C and 30-40 min. Germination decreased slightly from 68% at 5% SMC to 63% at 20% SMC (LSD 1.2) for all durations. The second experiment studied the effect of initial SMC and treatment durations on infestation of seed by Alternaria radicina and seed germination. Treatment at 50°C for 30 min for all SMC compared to the control resulted in a decrease in A. radicina infestation from 69.2 to 1.7%. Reducing SMC from 20 to 5% for all durations resulted in a small decrease in infestation from 25% to 18% (LSD 1.5). Reducing SMC to 5% prior to hot water treatment may be a commercially viable means of minimising reductions in seed viability and decreasing fungal infestation levels

The effect of seed moisture content and hot water treatment on carrot seed viability and Alternaria radicina control

Hot water treatment of seeds to control seedborne pathogens is an important tool for organic seed production. Reducing seed moisture content may have the potential to increase carrot (Daucus carota L. var. sativus D.C.) seed tolerance to treatment. Two hot water seed treatment experiments were conducted

The ability of the green peach aphid (Myzus persicae) to penetrate mesh crop covers used to protect potato crops against tomato potato psyllid (Bactericera cockerelli)

In Central and North America, Australia and New Zealand, potato (Solanum tuberosum) crops are attacked by Bactericera cockerelli, the tomato potato psyllid (TPP). 'Mesh crop covers' which are used in Europe and Israel to protect crops from insect pests, have been used experimentally in New Zealand for TPP control. While the covers have been effective for TPP management, the green peach aphid (GPA, Myzus persicae) has been found in large numbers under the mesh crop covers. This study investigated the ability of the GPA to penetrate different mesh hole sizes. Experiments using four sizes (0.15 × 0.15, 0.15 × 0.35, 0.3 × 0.3 and 0.6 × 0.6 mm) were carried out under laboratory conditions to investigate: (i) which mesh hole size provided the most effective barrier to GPA; (ii) which morph of adult aphids (apterous or alate) and/or their progeny could breach the mesh crop cover; (iii) would leaves touching the underside of the cover, as opposed to having a gap between leaf and the mesh, increase the number of aphids breaching the mesh; and (iv) could adults feed on leaves touching the cover by putting only their heads and/or stylets through it? No adult aphids, either alate or apterous, penetrated the mesh crop cover; only nymphs did this, the majority being the progeny of alate adults. Nymphs of the smaller alatae aphids penetrated the three coarsest mesh sizes; nymphs of the larger apterae penetrated the two coarsest sizes, but no nymphs penetrated the smallest mesh size. There was no statistical difference in the number of aphids breaching the mesh crop cover when the leaflets touched its underside compared to when there was a gap between leaf and mesh crop cover. Adults did not feed through the mesh crop cover, though they may have been able to sense the potato leaflet using visual and/or olfactory cues and produce nymphs as a result. As these covers are highly effective for managing TPP on field potatoes, modifications of this protocol are required to make it effective against aphids as well as TPP

Regenerative agriculture in Aotearoa New Zealand - research pathways to build science-based evidence and national narratives.

fals

Formal collaboration amongst four tertiary education institutions to advance environmental sustainability.

There is increasing awareness in the tertiary education sector in Australia and New Zealand that many of its activities are not environmentally sustainable and need to be changed. In most cases tertiary educational institutions (TEI) are working individually to address environmental sustainability (ES) while taking advantage of a range of information sources and networks, such as Australasian Campuses Towards Sustainability (ACTS) to help them achieve their ES aims. In the Canterbury region of New Zealand the four major TEIs have formed an official joint working group to address environmental sustainability on all their campuses. The Environmental Sustainability Working Group (ESWG) started in late 2003 as a grass roots network of staff and students who were interested in ES from the four institutions. The vision was to provide a forum for mutual support, sharing knowledge, information and experience, thereby resulting in faster implementation of ES initiatives at the member institutions. To give the group sufficient ‘authority’ to achieve its aims it was considered vital that the group be officially recognised by the institutions and have the support of senior management. This was achieved under the ‘umbrella’ organisation the Canterbury Tertiary Alliance (CTA) (www.cta.ac.nz). The CTA is a formal alliance between the University of Canterbury (UC), Lincoln University (LU), the Christchurch College of Education (CCE) and the Christchurch Polytechnic Institute of Technology (CPIT) and was formed in 2001. The aim of the CTA is “to ensure that Christchurch's four major providers develop tertiary education choices in Canterbury in a complementary way. This ensures cooperation in best practice, cost efficiencies, collegiality and ultimately benefits our students” (www.cta.ac.nz/news/cta1.pdf , examples of other CTA activities are joint purchasing initiatives for information technologies and libraries and reciprocal library borrowing rights). Terms of reference for the Environmental Sustainability Working Group (Figure 1) were endorsed by the CTA executive in June 2004. The CTA executive consists of the Vice Chancellors, Principal and Chief Executive of the member institutions and other senior managers. With this authority the ESWG moved on to develop it first major project: waste minimisation