Increase In Plot Size Research Articles

How can continuous land transfers guarantee food security? A study from the perspectives of plot size

ABSTRACT Continuous land transfer is an important direction for future agricultural policy in developing countries. However, there is little research on the impacts of land contiguity in China. Based on 2020 national micro-survey data, this paper analyzes the different focuses of land contiguity, divides contiguous transfers into connected and patchy transfers, and explores the differential impacts of the two on food production. The paper further explores how heterogeneous plot sizes play a role in it. The results are as follows: (1) connected transfer has a greater effect than patchy transfer; (2) contiguous transfers can secure food production by contributing to an increase in plot size, with continuous transfers contributing more to the maximum plot size; (3) maximum plot size has a positive effect on promoting food production; (4) continuous transfer performed better in terms of yield increase in non-plain and main grain-producing areas; and, (5) the ‘inverted U-shape’ impacts of patchy transfers on food production are evident. Therefore, the government should fully promote continuous land transfer while focusing on connected transfer, which should expand maximum plot size as much as possible. After continuous transfer, it should also be wary of the ‘non-food’ phenomenon in the plains.

Impacts of plot size on maize yields and farm profits: Implications for sustainable land use and food security

ABSTRACT This paper examines the impact of plot size on maize yields and farm profits, using plot-level data collected from Chinese maize farmers in 2013 and 2015. Unlike previous studies that have used either a parametric or non-parametric model, this study estimates a semi-parametric model. This model simultaneously estimates the impact of plot size on maize yields and farm profits non-parametrically and the impact of other control variables on the two outcome variables parametrically, which provides more insights. The findings reveal that plot size affects maize yields and farm profits differently. There is a ‘pan-shaped’ relationship between plot size and maize yields. Specifically, we show that when increasing plot size from 0.1 to 1.5 mu and then to 65 mu, the maize yields decrease first and then become stable. When plot size is above 65 mu, maize yields increase as plot size increases. In comparison, our results indicate that as plot size increases, the farm profits of maize production monotonically increase. Our findings have important implications for sustainable land use and food security.

Deciphering human and climatic controls on soil erosion in intensively cultivated landscapes after 1950 (Loire Valley, France)

Intensification of agricultural practices during the second half of the 20th century has accelerated soil erosion around the world. Although this phenomenon has been widely investigated through a combination of monitoring or modelling at short timescales (<10 years), few records are available for reconstructing the trajectory of soil erosion during longer periods (i.e. the 20th century). Analysis of sediment deposits in reservoirs provides a valuable tool for reconstructing these trends and for identifying the driving factors that may have disturbed the sediment cascade after 1950. Accordingly, sediment cores (n = 5) were collected in a reservoir located at the outlet of an intensively cultivated lowland catchment (24.5 km²) representative of those found in central France. Natural (excess lead-210) and artificial radionuclides (caesium-137, americium-241) enable dating of these sedimentary sequences. The corresponding sediment accumulation and erosion rates were calculated for the 1928–2017 period. In addition, daily rainfall records, land use change and agricultural field patterns were reconstructed for the period comprised between 1950 and 2017, based on weather records, digitalized aerial images (n = 10) and agricultural census data (n = 6). Results showed substantial acceleration of erosion rates after 1928 (+500 %). This increase occurred simultaneously with major landscape changes that led to an increase in plot size (+465 %) and decrease of the surface occupied by grassland and fallow land (-93 %). Both parameters correlated strongly with the erosion rates reconstructed in this catchment (r = 0.87 and r = 0.95 for the plot size and grassland/fallow land surfaces, respectively). In addition, spectral analyses of daily rainfall records and mass accumulation rates, estimated with a high temporal resolution from the sediment core tomography scanner data, showed concomitant short (i.e., 1 year) and long-term (i.e., 16 years) cycles between mass accumulation rates and rainfall. Overall, this study demonstrated the long-term impact of human activities and rainfall dynamics on soil erosion. Between 1928 and 2017, erosion rates increased seven-fold in this lowland catchment, until reaching 31.5 t km−2 yr-1 by 2017. Although landscape modifications likely drove the pluri-decadal trends of erosion, this study has also demonstrated the major role played by rainfall intensity on annual sediment dynamics.

Land Inequality, Gender Land Disparity and Poverty in Rural Africa

Over the past four decades, Zimbabwe redistributed vast quantities of arable land to the landless, women and poor communal farmers to reduce inequality. Yet poverty and gender disparity in land ownership have continued to be discernible. It is against this background that this article explores the relationship between poverty, gender disparity and land inequality using household survey data. First, the article assesses the state of inequality and gender disparity using descriptive statistics. Second, a regression discontinuity design is applied to evaluate the poverty impact of a marginal increase in plot size of a female-headed household from the existing mean of all women-headed households. Third, a simple regression is estimated to investigate the impact of land inequality and gender disparity on regional poverty levels. The results reveal a gender gap in landownership and a higher level of land inequality among female-headed households. But in the sub-sample of female-headed households, per capita consumption is larger and the proportion of poor households is smaller than in the sub-sample of male-headed households. The results further reveal that a transfer of arable land to women will only reduce poverty and promote equality if it targets women without land and those with less than 3 Acres. Spatially, poverty can be reduced by increasing the share of women owning arable land in regional districts. The major policy implication of the findings is that any land redistribution policy aiming at achieving gender equality in land ownership and reducing poverty must pay attention to women at the lower end of plot size distribution. There are substantial spillover benefits from addressing gender inequality in land ownership.

Determinants of smallholder farmers’ adoption of short-term and long-term sustainable land management practices

AbstractDespite increasing land degradation in sub-Saharan Africa, investment in sustainable land management (SLM) remains low. Empirical evidence show that smallholder farmers tend to prioritize investing in SLM practices with short-term turnover—e.g., composting and crop residue integration—in order to improve soil fertility and yields to the neglect of practices like agroforestry whose benefits tend to materialize in a relatively longer period. While it is crucial for farmers to prioritize both short-term and long-term SLM practices for the maintenance of overall ecosystem health, the factors that shape the concurrent adoption of short-term and long-term SLM practices remain underexplored. Using data from a cross-sectional survey with smallholder farming households (n = 512) in Malawi, we employed logistic regression to examine the determinants of the concurrent adoption of short-term and long-term SLM practices. Our findings show that plot size, farmer-to-farmer knowledge sharing, presence of a chronically ill person in the household, active household labor size, wealth and women's autonomy are noteworthy determinants. A unit increase in plot size was associated with increased odds (OR = 1.41, p &lt; 0.01) of simultaneously adopting short-term and long-term SLM practices. Similarly, a unit increase in the active labor size of the household (OR = 1.30, p &lt; 0.001) was positively associated with the concurrent adoption of short-term and long-term SLM practices. Households with no chronically sick person were 3.2 times more likely to adopt short-term and long-term SLM practices simulataneously compared to those with chronically sick persons. Farming households that exchanged farming information (OR = 2.50, p &lt; 0.001) with other households had significantly higher odds of adopting short-term and long-term SLM practices concurrently than those that did not share farming information. Compared to households in the poorest wealth category, those in the richer (OR = 3.14, p &lt; 0.001) and richest (OR = 3.64, p &lt; 0.001) wealth categories were both significantly more likely to adopt short-term and long-term SLM practices concurrently. These findings suggest that initiatives targeted at promoting the holistic adoption of SLM practices—a combination of both short-term and long-term practices—must pay attention to contextual nuances including household wealth, gender, farmer training and land access dynamics.

Optimum Size and Shape of Experimental Units for Cassava Cropping

In agricultural experimentation, the right size and shape of experimental units increase the precision of the experiment. This study determines the optimum size and shape of the experimental unit for field experimentation with cassava. For this, we carried out a uniformity test in Pacajús, Ceará, under dry conditions, with the cultivar 'Mastruço' planted at a spacing of 1.00 m x 0.60 m. The root yields were collected in 15 rows with 40 plants each, comprising 31 types of experimental units of 23 different pre-established sizes. The optimum size of the experimental unit was estimated by the Hatheway method, and the shape was determined by the relative information method. The Hatheway method indicated several optimum sizes of experimental units, many of which were applicable for evaluation experiments of cassava cultivars. The 15 x 1 rectangular experimental unit (15 rows with one plant and 9.00 m² of useful area) was considered the ideal shape for assessment of cassava production, which was smaller than the size suggested in surveys with of cassava cropping. There was a continuous nonlinear reduction of the coefficient of variation with the increase in plot size.

A focus on the European hamster to illustrate how to monitor endangered species.

Agriculture intensification, marked by the generalization of crop monoculture, by the increase in plot size and by the reduction of plant diversity, has led to huge decline in wildlife in European farmlands. In such habitat, research has long been biased towards birds and invertebrates, while very few studies have investigated the effect on small mammals. Considering the European hamster, Cricetus cricetus, we therefore review the different techniques that can be used to investigate the impact of environmental changes and conservation measures in small and endangered wild mammals. We suggest that only a multidisciplinary approach will allow exploration of these effects, combining experimental laboratory work on captive-bred animals with the monitoring of wild individuals. In particular, individual energy balance has to be investigated and measured as accurately as possible, through either biochemical or bio-logging techniques. It is, indeed, the most affected physiological trait in a changing environment, as it determines both the reproductive output and the survival of the individual. We also discuss the inconvenience of capture-release approaches for such an endangered species and emphasize the disturbance that experimental protocols could impose on the hamster.

Assessing the impacts of land fragmentation and plot size on yields and costs: A translog production model and cost function approach

More attentions should be focused on the changes in plot size of each household rather than the size of farmland in the discussions of economic problem of land fragmentation in China. This study empirically analyzes the impact of land fragmentation and plot size on yields, along with average costs, using household survey data collected from the Jiangsu province in China. A detailed and careful translog production model and cost function are employed to understand and analyze these problems. The empirical results reveal that there are increasing returns to scale in agricultural production. Land fragmentation reduces yields through changes in marginal outputs of agricultural inputs. Especially in areas with high opportunity costs of labor, the negative impact is more obvious. A one-unit increase in the Simpson index leads to a 39% increase in the average cost, whereas a one-unit increase in plot size leads to an 8% decline in the average cost. Thus, moderate expansion of the size of the plot can reduce the average cost, implying that agriculture can achieve economies of scale within each plot. Economies of scale should be developed by keeping farm size constant, reducing the number of plots, and expanding the size of each plot. We suggest that economies of scale can be achieved in each plot by either land consolidation or land transfer as well as by joint farming and joint association.

Land productivity and plot size: Is measurement error driving the inverse relationship?

This paper revisits the decades-old puzzle of the inverse plot-size productivity relationship (IR), which states that land productivity decreases as plot size increases. While existing studies define land productivity or yields as self-reported production divided by plot size, we consider an alternative approach to estimating yields based on crop cuts. The crop-cut method entails measuring and harvesting randomly selected subplots by trained technicians, and is recommended by the Food and Agricultural Organization for the accurate measurement of crop production. Using data of rural Ethiopia, our analysis indicates that the IR is strong when based on self-reported production, but disappears when based on crop-cut estimates. Our inference from these findings is that the IR is an artifact of systematic over-reporting of production by farmers on small plots, and under-reporting on larger plots. We also discuss how rejecting the inverse plot-size productivity relationship has significant implications for the inverse farm-size productivity relationship.

Shift from transport limited to supply limited sediment concentrations with the progression of monsoon rains in the Upper Blue Nile Basin

AbstractLong‐term erosion monitoring data in the Ethiopian highlands are only available from the Soil Conservation Research Program (SCRP) watersheds including the Anjeni watershed. The 113 ha Anjeni watershed was established in 1984 and fanya juu terraces were installed in 1986. Runoff and erosion data are available from three different plot sizes and at the watershed outlet. The objective of this study was to investigate how erosion processes and sediment rating parameters vary with plot size and the progression of the rainy monsoon phase. We analyzed runoff and sediment loss data from 40 plots and the watershed outlet. The dataset included erosion data from 24 newly constructed plots (3 m length) during the rainy monsoon phase of 2012 and 2013, and 16 long‐term plots (with 12, 16, 22, and 24% slopes and 3, 15 and 30 m lengths) and the watershed outlet during the period between 1986 to 1990. Sediment concentration (C) was fitted to runoff (Q) using a power regression equation (C = aQb). Sediment concentration and yield increased with increasing plot length from 3 m to 15 m, but sediment yield decreased as plot length increased to 30 m.The coefficients (a and b) were affected by plot size and the progression of the rainy monsoon phase. As plot size increases, the a value increased, while the b value decreased. Greater a values were observed during the beginning of the monsoon phase, while values of b were greater towards the end of the monsoon phase. Overall findings suggest that erosion from cultivated fields is primarily controlled by transport limitations at the beginning of the monsoon phase, while towards the end of the monsoon phase, as surface covers emerge, sediment availability will be reduced, and thus sediment source would be a limitation. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Do Land Characteristics Affect Farmers' Soil Fertility Management?

Soil fertility management (SFM) has important implications for sustaining agricultural development and food self-sufficiency. Better understanding the determinants of farmers' SFM can be a great help to the adoption of effective SFM practices. Based on a dataset of 315 plots collected from a typical rice growing area of South China, this study applied statistical method and econometric models to examine the impacts of land characteristics on farmers' SFM practices at plot scale. Main results showed that in general land characteristics affected SFM behaviors. Securer land tenure arrangements facilitated effective practices of SFM through more diversified and more soil-friendly cropping pattern choices. Plot size significantly reduced the intensities of phosphorus and potassium fertilizer application. Given other factors, 1 ha increase in plot size might reduce 3.0 kg ha−1 P2O5 and 1.8 kg ha−1 K2O. Plots far from the homestead were paid less attention in terms of both chemical fertilizers and manure applications. Besides, plots with better quality were put more efforts on management by applying more nitrogen and manure, and by planting green manure crops. Significant differences existed in SFM practices between the surveyed villages with different socio-economic conditions. The findings are expected to provide important references to the policy-making incentive for improving soil quality and crop productivity.

On optimum plot size and shape for field experimentation on brinjal (Solanum melongena L.) under middle Gujarat condition

Correspondence to : M.S. SHITAP Department of Agriculture Statistics, B.A. College of Agriculture, Anand Agricultural University, ANAND (GUJARAT) INDIA ABSTRACT : An uniformity trial on JBGR-1 of brinjal was conducted at the Main Vegetable Research Station, Anand Agricultural University, Anand to determine the optimum size and shape of the plot using maximum curvature method. The variability as judged by co-efficient of variation (CV) per unit area decreased with the increase in plot size. The optimum plot (net) size obtained and advocated was 6.48 sq. m. covering single row of 7.2 m length and spaced at 0.9 m (7.2 m × 0.9 m) for field experiments on brinjal under Anand condition.

UTLIZATION OF UNIFORMITY TRIALS TO ESTIMATE THE OPTIMUM PLOT SIZE AND SHAPE AND THE NUMBER OF REPLICATIONS IN WHEAT YIELD TRIALS

In the present work, two uniformity trials were carried out during thefirst and the second winter seasons of 2011/2012 and 2012/2013 in theExperimental farm Demo, Faculty of Agriculture, Fayoum University. Themain objectives were to estimate the optimum plot size, plot shape andnumber of replicates for wheat yield traits using the variety Sakha 93 as plantmaterial. The cultivated area of each field trial was divided into 12 strips;each of which consisted of 100 rows, 0.2 m width and 3.0 m long. Twostatistical methods including soil variability index and maximum curvaturewere used to estimate the optimum plot size and shape using the yield data of1200 basic units (each of 0.6 m2). The data were subjected to two proceduresof statistical analysis to estimate the optimum plot size, when the cost ofconducting the experiment is not taken into consideration and to evaluate theeffect of changing the plot shape on the variability. The first statistical methodwas that of maximum curvature which is based on the exponentialrelationship between plot size and the coefficient of variability. The secondmethod was that developed by smith’s method (1938). Bartlett's test forhomogeneity of variances, as outlined by Steel and Torrie (1980), was usedto study the effect of changing plot shape. The obtained results could besummarized as follows: Increasing the plot size decreased the variance perbasic unit and the coefficient of variability. However, the reduction was not inproportion with the increase in plot size. The index of soil variability rangedfrom 0.6433 to 0.6018 as an average for the 1st and the 2nd seasons,respectively. The relationship between the coefficient of variability (C.V.)and plot size (X) were mathematically expressed by the following equationC.V. = 19.21 X-0.2595 for the 1st season and C.V. = 19.60 X – 0.2725 for the 2ndone. Accordingly, using the soil variability index, the optimum plot size was2 basic units (1/3500 fed.) for the two seasons, while it was 4 basic units(1/1750 fed.) in both seasons when the maximum curvature method wasapplied. The required number of replications for the optimum plot size usingSmith method detecting a 15% difference among treatment means varied 13and 14 in the 1st and the 2nd seasons, respectively. But, for detecting a 20%difference among treatment means, 7 replications in the 1st season and 8replications in the 2nd one were found necessary. Optimum plot size estimatedusing the maximum curvature method detecting a 15% difference amongtreatment means varied 7 and 8 in the 1st and the 2nd seasons, respectively. But, for detecting a 20% difference among treatment means, 4 replications inthe 1st and 2nd season's one were found necessary. Generally, the plot shapedid not affect on the precision of wheat yield trial in most cases in the twogrowing seasons.

Low-cost microirrigation system supplied by groundwater: An application to pepper and vineyard crops in Spain

The PRESUD tool was developed using MATLAB™ to identify the optimum microirrigation system design. The lowest cost was determined by calculating the annual water application cost per unit of irrigated area (CT). This is defined as the cost of one cubic meter of water applied to crops, and is the sum of investment (Ca), maintenance (Cm) and energy (Ce) costs. This tool optimizes the shape of the characteristic and efficiency curves of the pump and the pumping pipe, distribution pipe, and irrigation system pipes diameters with a holistic approach.All subunits are rectangular, with the well pipe in the center. The lateral and manifold pipe parameters are calculated using a stepwise method. The analysis includes the effects of the main factors in irrigation system design: dynamic lift in the aquifer (DL), number of subunits (NS), irrigated area (S) and crop irrigation water requirements (Rg), among others.The tool was applied to the specific conditions in Spain. Results show that CT decreases with an increase in plot size, and costs are high for plots smaller than 3–5ha. This is due to the percentage of total costs that the tube well and electrical line contribute. CT has a positive relationship with DL. In these case studies, diesel fuel electrical generators are recommended for plots <4ha for pepper crops and up to 15ha for grapevine if DL is 40m. These limits vary with different DL values or changes in the cost and length of the electrical line.

Experimental strategies in carrying out VCU for tobacco crop I: plot design and size

We aimed to establish standards for tobacco Valor de Cultivo e Uso (VCU) in Brazil. We obtained information regarding the size and design of plots of two varietal groups of tobacco (Virginia and Burley). Ten inbred lines of each varietal group were evaluated in a randomized complete block design with four replications. The plot contained 42 plants with six rows of seven columns each. For each experiment plant, considering the position of the respective plant in the plot (row and column) as a reference, cured leaf weight (g/plant), total sugar content (%), and total alkaloid content (%) were determined. The maximum curvature of the variations in coefficients was estimated. Trials with the number of plants per plot ranging from 2 to 41 were simulated. The use of a border was not justified because the interactions between inbred lines x position in the plots were never significant, showing that the behavior of the inbred lines coincided with the different positions. The plant performance varied according to the column position in the plot. To lessen the effect of this factor, the use of plots with more than one row is recommended. Experimental precision, evaluated by the CV%, increased with an increase in plot size; nevertheless, the maximum curvature of the variation coefficient method showed no expressive increase in precision if the number of plants was greater than seven. The result in identification of the best inbred line, in terms of the size of each plot, coincided with the maximum curvature method.

Species constancy depends on plot size – a problem for vegetation classification and how it can be solved

AbstractQuestion: While it is well known that species richness depends on plot size, it is not generally recognised that the same must be true for constancy. Accordingly, many authors use varying plot sizes when classifying vegetation based on the comparison of constancies between groups of plots. We ask whether the constancy‐area relationship follows a general rule, how strong the effect of plot sizes is on constancies, and if it is possible to correct constancies for area.Location: For empirical evaluation, we use data from plant communities in the Czech Republic, Sweden and Russia.Methods: To assess the potential influence of differences in plot size on constancies, we develop a mathematical model. Then, we use series of nested plot species richness data from a wide range of community types (herbaceous and forest) to determine the parameters of the derived function and to test how much the shape of the constancy‐area relationship depends on taxa or vegetation types.Results: Generally, the constancy‐area relationship can be described by C (A)=1−(1−C0)(A/A0)^d, with C being constancy, A area, C0 known constancy on a specific area A0, and d a damping parameter accounting for spatial autocorrelation. As predicted by this function, constancies in plant communities always varied from values near 0% to near 100% if plot sizes were changed sufficiently. For the studied vegetation types, a two‐ to fourfold increase in plot size resulted in a change of conventional constancy classes, i.e. an increase of constancy by 20% or more.Conclusions: Vegetation classification, which largely relies on constancy values, irrespective of whether traditional or modern fidelity definitions are used, is strongly prone to distorting scale effects when relevés of different plot sizes are combined in studies. The constancy‐area functions presented allow an approximate transformation of constancies to other plot sizes but are flawed by idiosyncrasies in taxa and vegetation types. Thus, we conclude that the best solution for future surveys is to apply uniform plot sizes within a few a priori delimited formations and to determine diagnostic species only within these formations. Finally, we suggest that more detailed analyses of constancy‐area relationships can contribute to a better understanding of species‐area relationships because the latter are the summation of the first for all species.

Modelling forest succession in two southeastern Canadian mixedwood ecosystem types using the ZELIG model

The gap model ZELIG was validated for red spruce–balsam fir–yellow birch and yellow birch–sugar maple–balsam fir forest types in southern Quebec, Canada. Long-term historical data originating from the Lake Edward Experimental Forest, La Mauricie National Park, were used. The effect of the variation in plot size, representing the space within which trees uptake site resources, was also examined. Several species were included in both forest types: red spruce ( Picea rubens Sarg.), balsam fir ( Abies balsamea (L.) Mill.), yellow birch ( Betula alleghaniensis Britton), white birch ( Betula papyrifera Marsh.), red maple ( Acer rubrum L.), sugar maple ( Acer saccharum Marsh.), American beech ( Fagus grandifolia Ehrh.), eastern hemlock ( Tsuga canadensis (L.) Carr.) and northern white cedar ( Thuja occidentalis L.). The pattern of change in basal area growth varied among species, ranging from a steady increase to a more or less rapid decline. There was a good agreement between observations and predictions for yellow birch, red spruce, red maple, sugar maple, balsam fir and northern white cedar. Plot size had a significant impact on the dynamics of the different species. Depending on the species, the decline was accelerated, the amplitude of the fluctuations varied, or the maximum basal area reached changed. Predicted regeneration varied among species and the number of seedlings generally increased with increase in plot size. The pattern of development for most species was related to their life characteristics. The results highlighted the fact that there is a critical lack of knowledge and data on the dynamics of regeneration from the seedling to the sapling stages for the two forest types studied, which resulted in poor predictions for some species. As the life characteristics varied among species, the use of only one plot size for all species may not be realistic.

Optimum Plot Size in Field Experiments with Strawberries

Abstract Optimum plot size is a function of costs and precision. As plot size increases, up to a limit, there is a gradual improvement in precision expressed in terms of a plot variance while higher costs are entailed. The common measure linking all the sources of environmental variability in field trials is Smith'S index of soil heterogeneity b. In the present study two methods of evaluation of bhave been applied. Koch and Rigney'S formula enables the calculation of bfrom replicated experiments using estimates of variances associated with different plot sizes (the size of a block, main plot or sub-plot). Lin and Binns' proposal bases bon an adjusted Smith'S formula (with a “correction factor” for the number of plots in a block) and the coefficient of intraclass correlation (estimated from variance components). Slightly higher values of bderived in the present study from Lin and Binns' method in comparison with that of Koch and Rigney were probably due to including the “correction factor.” In our strawber...

Uniformity trial with lucerne grown for fodder

AbstractData on the yield of lucerne for individual cuts and the total for three cuts from a uniformity trial were analysed. It was observed that CV% values decreased with the increase in plot size, both for each cut and for total yield. The decrease was considerable up to a plot size of 8 to 16 m2. The plot shape did not show any consistent effect. Increasing the size of block resulted in increased CV values, but block shape had no consistent effect. The CV values were highest for the first cut and lowest for the second cut. A relationship between the average CV% and plot size was found. However, this relationship, or its modified form Y= a.X1−b1. X2−b2 taking into account the plot shape and considering the individual CV values, provide a good fit to the data for the cases where blocking was adopted. The coefficient of heterogeneity was less than 0·29, being lowest for first‐cut yields, followed by the total, the third cut and the second cut yields. This showed a high degree of positive correlation between yields of neighbouring plots. Blocking proved useful in increasing the efficiency of the experiment and it is suggested that block size may be kept at 8 or less plots per block. The relationship between average CV% and block size was of the from Y = a Xb. The present study suggests that, for field experiments with luceme, the plot size may be kept to a minimum that does not exceed 8 to 12 m2, in blocks of eight to nine plots with the shapes of plots and blocks being nearly square. Calculating the efficiencies of confounded factorial design and incomplete block design revealed that block size may be kept to a minimum. The recovery of interblock information was found useful and balancing may be attempted, but only, if necessary.

Sampling Quackgrass (Elytrigia repens) Populations

This work was initiated to develop a method of sampling quackgrass populations. Shoot and bud distribution of 36 field populations was obtained. The results demonstrated that shoot count was inappropriate in assessing quackgrass bud populations and that bud sampling depth should be at least 20 cm if an accurate estimate is required. When shoot count is the only possibility, quadrat size should be as large as possible to minimize the error. Descriptive statistics of the field populations were used to generate a series of 24 simulated quackgrass bud populations. The field and simulated data were computer sampled with a program designed to compare the effects of varying sample size (number of quadrats) and sample shape (quadrat size and form). The intensity of sampling must be a function of resources and cost, since sampling precision increased linearly with sample size. Precision of sampling was generally higher when a large number of small quadrats were used compared to a small number of large quadrats. Sampling intensity per unit area must be increased when bud density increases to maintain a given degree of precision, but it can be decreased when plot size increases.