title: Effect of winter cover crops on nutrition and weeds of maize

authors: Sakala, Aaron

subjects: cover crops

abstract: Cover crops are being used in New Zealand to manage soil nutrients and weeds and can have positive or negative effects on the growth of the following main crop. 
This study investigated the causes of lower yield of maize following a ryegrass cover crop compared to fallow or other cover crops at the Foundation for Arable Research Northern Crop Research site. Cover crops were sown in mixtures faba (Vicia faba L.), gland clover (Trifolium glanduliferum Boiss.) and rye (Lolium perenne L.) with fallow as a control and followed by maize. The effects on soil carbon to nitrogen ratios, and maize growth, yield and nutrition were monitored. Additional experiments in the laboratory and glasshouse investigated the effect of cover crops on weed seed germination. 
Winter cover crops affected nutrient dynamics during growth of the maize crop. The total soil carbon to nitrogen (CN) ratio decreased as the proportion of clover in the cover crop mix increased. In the fallow and clover treatments nutrients were available earlier for maize to grow rapidly, resulting in higher yields compared to the rye and rye faba treatments. In the rye treatment, the CN ratio had fallen and nutrients had become available to the crop by harvest time, resulting in lower maize tissue CN ratios and higher tissue nutrient contents. Rye had a clear effect on the CN ratio in the cover crop mix whether sown at full rate or half rate. Rye also appeared to suppress clover and faba in the mixed treatments, possibly reducing the potential for supplementation of nutrients through the nitrogen fixation process. A clover-based cover crop was better than a rye-based cover crop, probably because it resulted in a lower soil CN ratio and higher extractable soil nitrogen at the time of establishment of the main crop, and may therefore release nutrients faster for the benefit of the main crop. 
A laboratory experiment tested the inhibition effect of cover crop extracts on the germination of weed and crop species. Five gram aliquots of cover crop powder were soaked for 24 hours in 100 ml of water and the filtered extracts diluted before application to seeds of a range of test species. Cover crop extracts almost always inhibited seed germination, by up to approximately 40%, but the inhibitory effects on seed germination varied with the species of cover crop and the test species. Serial dilution of extracts indicated that there was a dose response effect in the level of germination suppression by the cover crop species. Clover had the largest potential for reducing the weed and crop species germination and therefore was the most promising cover crop for exhibiting a true allelopathic effect on weed seed germination.
To further test the inhibition effect of clover and rye cover crops on germination of weed and crop species in the soil, root and shoot residues were tested on seeds of weed and crop species planted in pots. Root residues inhibited germination of volunteer and planted test species more than shoot residues, possibly because of a higher availability of inhibitory compounds, or because of differences in the time of setting up the root and shoot pots. The inhibitory effect on germination exerted by cover crop varied with the test species. This was shown by inhibition affecting one species but not others, which might suggest that some species were more sensitive to a particular cover crop treatment. Cover crop roots were more likely to affect germination, but cover crop shoots were more likely to reduce the growth of planted test species. The lack of a root effect on growth might be explained by loss or dilution of any allelopathic compounds that affected germination, or because their mode of action was specific to germination.
Overall, clover root and shoot treatments have the potential to inhibit germination and growth of weed and crop species. The results support the hypothesis that clover either as a crop residue or as an extract has a higher potential to suppress germination of other species compared to rye and is the most promising cover crop for exhibiting a true allelopathic effect on germination of weed seeds. It was also shown that a clover-based winter cover crop might be better than a rye-based cover crop in terms of its effects on nutrient availability to the main crop. The results have implications for the decision to keep crop residues in the field to reduce the germination and growth of weeds. There may be an economic benefit from using cover crop shoots for other activities (e.g. silage or cut-and-carry forage) while still benefiting from the weed controlling effects of roots residues that are left in the field. Further experiments on the effects of winter cover crops for maize production in New Zealand are recommended.

text: Effect of winter cover crops on nutrition and weeds of maize Cover crops are being used in New Zealand to manage soil nutrients and weeds and can have positive or negative effects on the growth of the following main crop. 
This study investigated the causes of lower yield of maize following a ryegrass cover crop compared to fallow or other cover crops at the Foundation for Arable Research Northern Crop Research site. Cover crops were sown in mixtures faba (Vicia faba L.), gland clover (Trifolium glanduliferum Boiss.) and rye (Lolium perenne L.) with fallow as a control and followed by maize. The effects on soil carbon to nitrogen ratios, and maize growth, yield and nutrition were monitored. Additional experiments in the laboratory and glasshouse investigated the effect of cover crops on weed seed germination. 
Winter cover crops affected nutrient dynamics during growth of the maize crop. The total soil carbon to nitrogen (CN) ratio decreased as the proportion of clover in the cover crop mix increased. In the fallow and clover treatments nutrients were available earlier for maize to grow rapidly, resulting in higher yields compared to the rye and rye faba treatments. In the rye treatment, the CN ratio had fallen and nutrients had become available to the crop by harvest time, resulting in lower maize tissue CN ratios and higher tissue nutrient contents. Rye had a clear effect on the CN ratio in the cover crop mix whether sown at full rate or half rate. Rye also appeared to suppress clover and faba in the mixed treatments, possibly reducing the potential for supplementation of nutrients through the nitrogen fixation process. A clover-based cover crop was better than a rye-based cover crop, probably because it resulted in a lower soil CN ratio and higher extractable soil nitrogen at the time of establishment of the main crop, and may therefore release nutrients faster for the benefit of the main crop. 
A laboratory experiment tested the inhibition effect of cover crop extracts on the germination of weed and crop species. Five gram aliquots of cover crop powder were soaked for 24 hours in 100 ml of water and the filtered extracts diluted before application to seeds of a range of test species. Cover crop extracts almost always inhibited seed germination, by up to approximately 40%, but the inhibitory effects on seed germination varied with the species of cover crop and the test species. Serial dilution of extracts indicated that there was a dose response effect in the level of germination suppression by the cover crop species. Clover had the largest potential for reducing the weed and crop species germination and therefore was the most promising cover crop for exhibiting a true allelopathic effect on weed seed germination.
To further test the inhibition effect of clover and rye cover crops on germination of weed and crop species in the soil, root and shoot residues were tested on seeds of weed and crop species planted in pots. Root residues inhibited germination of volunteer and planted test species more than shoot residues, possibly because of a higher availability of inhibitory compounds, or because of differences in the time of setting up the root and shoot pots. The inhibitory effect on germination exerted by cover crop varied with the test species. This was shown by inhibition affecting one species but not others, which might suggest that some species were more sensitive to a particular cover crop treatment. Cover crop roots were more likely to affect germination, but cover crop shoots were more likely to reduce the growth of planted test species. The lack of a root effect on growth might be explained by loss or dilution of any allelopathic compounds that affected germination, or because their mode of action was specific to germination.
Overall, clover root and shoot treatments have the potential to inhibit germination and growth of weed and crop species. The results support the hypothesis that clover either as a crop residue or as an extract has a higher potential to suppress germination of other species compared to rye and is the most promising cover crop for exhibiting a true allelopathic effect on germination of weed seeds. It was also shown that a clover-based winter cover crop might be better than a rye-based cover crop in terms of its effects on nutrient availability to the main crop. The results have implications for the decision to keep crop residues in the field to reduce the germination and growth of weeds. There may be an economic benefit from using cover crop shoots for other activities (e.g. silage or cut-and-carry forage) while still benefiting from the weed controlling effects of roots residues that are left in the field. Further experiments on the effects of winter cover crops for maize production in New Zealand are recommended.

year: 2019

title: A capabilities approach to freedom of employment: Hierarchical capabilities

authors: Blight, Damian

subjects: Capabilities approach

abstract: When people in New Zealand are unhappy with their current employment, they are often advised to find a new job. Implicit here is the assumption that a new job will be better, but it is not entirely clear that this is always the case. In this thesis I aim to navigate the complexities of this suggestion in order to ascertain whether or not the task of finding new employment, that is more meaningful to the individual, is as simple as it sounds. To do this I have developed a hierarchical chart, in combination with the capabilities approach from Amartya Sen. The capabilities approach allows us to focus on the options that are available to the individual, rather than ensuring that everyone is given access to everything, including things that they do not need. By looking at freedom of employment as a capability, we may identify meaningful options for individuals even if some options are closed off to them. However, if there are not enough available options then individuals may lack access to meaningful freedom of employment.
By ordering the capabilities that are required for individuals to enjoy meaningful freedom of employment into a hierarchy, I am able to structure them such that any necessary capabilities can be investigated based on how many available options individuals have to achieve them. I will investigate three main groups of capabilities that are required by individuals in their pursuit of meaningful freedom of employment; find meaningful employment, achieve education and training, and receive adequate government intervention, to see if there are adequate options available for individuals to have access to meaningful freedom of employment. Employment plays a large role in the ability of individuals to live a life that is meaningful to themselves. For this reason, it is important that individuals have access to freedom of employment in a meaningful way.
The capabilities of individuals may be obstructed through power discrepancies between the government, employers and employees, which the capabilities approach is able to highlight. In later chapters I will discuss who ought to keep their finger on the scale and offer some suggestions in the conclusion as to how this may be achieved. Using this approach, I hope to provide some additional insight into the complexities of meaningful employment, which may be used to develop new policies to ensure access to the capabilities that are required for meaningful freedom of employment for everyone who resides in New Zealand.

text: A capabilities approach to freedom of employment: Hierarchical capabilities When people in New Zealand are unhappy with their current employment, they are often advised to find a new job. Implicit here is the assumption that a new job will be better, but it is not entirely clear that this is always the case. In this thesis I aim to navigate the complexities of this suggestion in order to ascertain whether or not the task of finding new employment, that is more meaningful to the individual, is as simple as it sounds. To do this I have developed a hierarchical chart, in combination with the capabilities approach from Amartya Sen. The capabilities approach allows us to focus on the options that are available to the individual, rather than ensuring that everyone is given access to everything, including things that they do not need. By looking at freedom of employment as a capability, we may identify meaningful options for individuals even if some options are closed off to them. However, if there are not enough available options then individuals may lack access to meaningful freedom of employment.
By ordering the capabilities that are required for individuals to enjoy meaningful freedom of employment into a hierarchy, I am able to structure them such that any necessary capabilities can be investigated based on how many available options individuals have to achieve them. I will investigate three main groups of capabilities that are required by individuals in their pursuit of meaningful freedom of employment; find meaningful employment, achieve education and training, and receive adequate government intervention, to see if there are adequate options available for individuals to have access to meaningful freedom of employment. Employment plays a large role in the ability of individuals to live a life that is meaningful to themselves. For this reason, it is important that individuals have access to freedom of employment in a meaningful way.
The capabilities of individuals may be obstructed through power discrepancies between the government, employers and employees, which the capabilities approach is able to highlight. In later chapters I will discuss who ought to keep their finger on the scale and offer some suggestions in the conclusion as to how this may be achieved. Using this approach, I hope to provide some additional insight into the complexities of meaningful employment, which may be used to develop new policies to ensure access to the capabilities that are required for meaningful freedom of employment for everyone who resides in New Zealand.

year: 2021

title: My responsibility in the face of mass extinction

authors: Gray-Sharp, Katarina

subjects: autoethnography

abstract: Extinction is the “irreversible condition of a species or other group of organisms having no living representatives in the wild, which follows the death of the last surviving individual of that species or group” (Hine and Martin 2015g, para. 1). Mass extinctions are extinctions of the greatest magnitude, occurring “when many diverse groups of organisms become extinct over short periods of time” (Condie 2011, 250). These “are not step-events but rather a step into a prolonged alternative global ecosystem state” (Hull 2015, R941). Five mass extinctions have previously been recorded. A sixth has begun. Humans are the cause of the latest episode.

This thesis develops an Indigenous, non-agential conception of responsibility for considering an ethical problem of wide consequence. Founded in mātauranga Māori and recalling the work of Emmanuel Levinas, it applies Kaupapa Māori autoethnography, narrative, and conceptual analyses alongside exegeses and a replication study. Investigations of responsibility across various positions are encountered: those found in place and polity, those made as visitor and the commanded, those gifted as inherited erudition and in the suffering-with. Now facing the last structural violence, what is my responsibility?

text: My responsibility in the face of mass extinction Extinction is the “irreversible condition of a species or other group of organisms having no living representatives in the wild, which follows the death of the last surviving individual of that species or group” (Hine and Martin 2015g, para. 1). Mass extinctions are extinctions of the greatest magnitude, occurring “when many diverse groups of organisms become extinct over short periods of time” (Condie 2011, 250). These “are not step-events but rather a step into a prolonged alternative global ecosystem state” (Hull 2015, R941). Five mass extinctions have previously been recorded. A sixth has begun. Humans are the cause of the latest episode.

This thesis develops an Indigenous, non-agential conception of responsibility for considering an ethical problem of wide consequence. Founded in mātauranga Māori and recalling the work of Emmanuel Levinas, it applies Kaupapa Māori autoethnography, narrative, and conceptual analyses alongside exegeses and a replication study. Investigations of responsibility across various positions are encountered: those found in place and polity, those made as visitor and the commanded, those gifted as inherited erudition and in the suffering-with. Now facing the last structural violence, what is my responsibility?

year: 2021