Soil organic carbon and root distribution in a temperate arable agroforestry system

Aim To determine, for arable land in a temperate area, the effect of tree establishment and intercropping treatments, on the distribution of roots and soil organic carbon to a depth of 1.5 m. Methods A poplar (Populus sp.) silvoarable agroforestry experiment including arable controls was established on arable land in lowland England in 1992. The trees were intercropped with an arable rotation or bare fallow for the first 11 years, thereafter grass was allowed to establish. Coarse and fine root distributions (to depths of up to 1.5 m and up to 5 m from the trees) were measured in 1996, 2003, and 2011. The amount and type of soil carbon to 1.5 m depth was also measured in 2011. Results The trees, initially surrounded by arable crops rather than fallow, had a deeper coarse root distribution with less lateral expansion. In 2011, the combined length of tree and understorey vegetation roots was greater in the agroforestry treatments than the control, at depths below 0.9 m. Between 0 and 1.5 m depth, the fine root carbon in the agroforestry treatment (2.56 t ha-1) was 79% greater than that in the control (1.43 t ha-1). Although the soil organic carbon in the top 0.6 m under the trees (161 t C ha-1) was greater than in the control (142 t C ha-1), a tendency for smaller soil carbon levels beneath the trees at lower depths, meant that there was no overall tree effect when a 1.5 m soil depth was considered. From a limited sample, there was no tree effect on the proportion of recalcitrant soil organic carbon. Conclusions The observed decline in soil carbon beneath the trees at soil depths greater than 60 cm, if observed elsewhere, has important implication for assessments of the role of afforestation and agroforestry in sequestering carbon

Neglecting the history of the Rule of Law:(Unintended) Conceptual eugenics

In this short paper I provide a justificatory argument for the importance of the endeavour exemplified by the papers that comprise the remainder of this special issue. I suggest that consideration and assessment of the origins of the concept of the Rule of Law not only matters, but also that it is a practice that is often neglected. Further, I suggest our failure to take account of the origins of the Rule of Law—by continuing to simply innovate around the idea of the contemporary understanding of the concept—limits the concept’s future development and will, potentially, not reflect faithfully the ideas from which our contemporary understanding of the concept is ultimately derived. As a result of this failure, we risk the (unintentional) imposition of a selective approach in the interpretation and application of the concept of the Rule of Law in the future. Increasing our focus on the origins of the Rule of Law will not only illuminate the rationale for and behind the operation of the concept, but it will also expose aspects of the concept that are no longer considered or included—in contemporary conceptions of the idea—and will ensure our future solutions are not curtailed

Evaluating the Impact of Performance-related Pay for Teachers in England.

This paper evaluates the impact of a performance-related pay scheme for teachers in England. Using teacher level data, matched with test scores and value-added, we test whether the introduction of a payment scheme based on pupil attainment increased teacher effort. Our evaluation design controls for pupil effects, school effects and teacher effects, and adopts a difference-in-difference methodology. We find that the scheme did improve test scores and value added, on average by about half a grade per pupil. We also find heterogeneity across subjects, with maths teachers showing no improvement.Incentives, teachers pay, education reform, pupil attainment

Agroforestry in the UK

The Royal Forestry Society, the Woodland Trust and the Soil Association are hosting a one-day conference on ‘Agroforestry: Improving Productivity for Farmers and Foresters’ at Cranfield University, Bedfordshire on 22 June 2017. This will be followed by a one-day Farm Woodland Forum workshop, including a field visit to the apple and cereal agroforestry system of Stephen Briggs. To set these events in context, this article explains why UK agroforestry is important, topical, how it is being used to market food products, improve productivity, address climate-change and flood management, and how it depends on dynamic farmers and foresters

An overview of tea research in Tanzania - with special reference to the Southern Highlands.

The history of tea development in Tanzania from the early part of this century to the present is summarised. Average yields of made tea from well managed estates in the Mufindi district have increased from around 600 kg ha-1 in the late 1950s to 3000 kg ha-1 at the present time: by comparison, yields from smallholder farms have remained much lower, averaging only 400-500 kg ha-1. There have been a large number of technical, economic and other changes over the last 30 to 40 years. The removal of shade trees, the use of herbicides, the application of NPK compound fertilisers, the introduction of irrigation (on some estates) and changes in harvesting policy have all contributed to the increases in yield. Financial and infrastructural problems have contributed to the low yields from many smallholders and others, and have limited the uptake of new technology. The contribution of research is reviewed, from the start of the Tea Research Institute of East Africa in Kenya in 1951, through to the development of the Marikitanda Tea Research Centre in Amani in 1967; the Ngwazi Tea Research Unit in Mufindi (1967 to 1970, and from 1986), and lastly the Kifyulilo Tea Research Station, also in Mufindi in 1986. The yield potential of well fertilized and irrigated clonal tea, grown at an altitude of 1800 m, is around 6000 kg ha-1. This potential is reduced by drought, lack of fertilizer, bush vacancies and inefficient harvesting practices. The corresponding potential yields at high (2200 m) and low (1200 m) altitude sites range from 3000-3500 kg ha-1 up to 9000-10000 kg ha-1 and are largely a function of temperature. The opportunities for increasing yields of existing tea, smallholder and estate, are enormous. Tea production in the Southern Highlands of Tanzania is about to expand rapidly. Good, appropriate research is needed to sustain this development over the long term, and suggestions on how best this is done in order to assist the large scale producers as well as the smallholders, are discussed

Maternity Rights and Mothers' Return to Work

In this paper we use the ALSPAC cohort of 12,000 births to examine the effect of maternity rights on mothers' post-birth return to employment decisions. We aim to disentangle the effects of the terms of maternity rights entitlements from the effects of other factors (such as household wealth, personal preferences and labour market opportunities) that influence the timing of a mother's return to work. We adopt a discrete hazard model with instrumental variables to estimate a counterfactual of what mothers with rights would have done in the absence of this legislation. Mothers with rights have an underlying (but unobserved) stronger attachment to the labour market which prompts earlier return than on average. Nevertheless, even when we take this into account we find a substantial impact of maternity rights on behaviour. Having rights induces around 20 per cent more women to return to their previous job before 7 months than would otherwise be the case. Women from lower skilled groups return disproportionately at the date at which maternity pay expires, while managerial and professional women tend to return at the expiry of unpaid leave.government policy, welfare, child care, labor supply

Advances in European agroforestry: results from the AGFORWARD project

In global terms, European farms produce high yields of safe and high quality food but this depends on the use of many off-farm inputs and the associated greenhouse gas emissions, loss of soil nutrients and other negative environmental impacts incur substantial societal costs. Farmers in the European Union receive support through a Common Agricultural Policy (CAP) that comprises direct payments to farmers (Pillar I) and payments related to rural development measures (Pillar II). This paper examines the ways in which agroforestry can support European agriculture and rural development drawing on the conclusions of 23 papers presented in this Special Issue of Agroforestry Systems which have been produced during a 4-year research project called AGFORWARD. The project had the goal of promoting agroforestry in Europe and focused on four types of agroforestry: (1) existing systems of high nature and cultural value, and agroforestry for (2) high value tree, (3) arable, and (4) livestock systems. The project has advanced our understanding of the extent of agroforestry in Europe and of farmers’ perceptions of agroforestry, including the reasons for adoption or non-adoption. A participatory approach was used with over 40 stakeholder groups across Europe to test selected agroforestry innovations through field trials and experiments. Innovations included improved grazing management in agroforestry systems of high nature and cultural value and the introduction of nitrogen fixing plants in high value timber plantations and olive groves. Other innovations included shelter benefits for arable crops, and disease-control, nutrient-retention, and food diversification benefits from integrating trees in livestock enterprises. Biophysical and economic models have also been developed to predict the effect of different agroforestry designs on crop and tree production, and on carbon sequestration, nutrient loss and ecosystems services in general. These models help us to quantify the potential environmental benefits of agroforestry, relative to agriculture without trees. In view of the substantial area of European agroforestry and its wider societal and environmental benefits, the final policy papers in this Special Issue argue that agroforestry should play a more significant role in future versions of the CAP than it does at present

A comparison of the responses of mature and young clonal tea to drought.

To assist commercial producers with optimising the use of irrigation water, the responses to drought of mature and young tea crops (22 and 5 years after field planting respectively) were compared using data from two adjacent long-term irrigation experiments in Southern Tanzania. Providing the maximum potential soil water deficit was below about 400-500 mm for mature, and 200-250 mm for young plants (clone 6/8), annual yields of dry tea from rainfed or partially irrigated crops were similar to those from the corresponding well-watered crops. At deficits greater than this, annual yields declined rapidly in young tea (up to 22 kg (ha mm)-1) but relatively slowly in mature tea (up to 6.5 kg (ha mm)- 1). This apparent insensitivity of the mature crop to drought was due principally to compensation that occurred during the rains for yield lost in the dry season. Differences in dry matter distribution and shoot to root ratios contributed to these contrasting responses. Thus, the total above ground dry mass of well-irrigated, mature plants was about twice that for young plants. Similarly, the total mass of structural roots (>1 mm diameter), to 3 m depth, was four times greater in the mature crop than in the young crop and, for fine roots (<1 mm diameter), eight times greater. The corresponding shoot to root ratios (dry mass) were about 1:1 and 2:1 respectively. In addition, each unit area of leaf in the canopy of a mature plant had six times more fine roots (by weight) available to extract and supply water than did a young plant. Despite the logistical benefits resulting from more even crop distribution during the year when crops are fully irrigated, producers currently prefer to save water and energy costs by allowing a substantial soil water deficit to develop prior to the start of the rains, up to 250 mm in mature tea, knowing that yield compensation will occur later