Optimising harvest date in sugar production: a case study for the Mossman mill region in Australia: II. Sensitivity to crop age and crop class distribution

Optimisation of harvest date in sugarcane production has been shown to increase productivity and profitability. This paper assesses the sensitivity of these responses to crop class and age distribution at harvest, using the Mossman mill region as a case study. Analyses were conducted to assess the consequences of different number of ratoons before ploughing out various fixed crop ages at harvest; and the advantages of fallowing before planting compared to ploughout and immediate replant. Productivity and profitability were found to be sensitive to modifications in model input parameters and constraints. The optimal number of ratoons to maximise both sugar yield and net revenue was found to be three. While the optimal cane supply was not very sensitive to constraints on crop age when it was restricted to 12 months plus or minus 2, there was a significant reduction in net revenue (4 to 5%) when restricted to younger and older crops (9 to 13 and 11 to 15 months). Comparisons of fallow verses ploughout replant showed a gain of 16% in net revenue when all crops were immediately planted after ploughout. This suggests that current fallowing practices are not financially beneficial in the case study region of coastal Mossman. The analysis methodology can be applied in other regions to identify better ways of scheduling cane supply.     

The influence of defoliation date and harvest interval on the quality of potatoes for french fry production

Summary Trials were carried out in 1984, 1985 and 1986 in which the effect of four dates of defoliation (0, +10, +20, +30 days) and three intervals to harvest (0, +10, +20 days) on yield, tuber size, dry matter, reducing sugar, fry test colour and finish fried sensory quality were examined for two cultivars (Pentland Dell, Maris Piper) on two sites (medium silt, peaty loam). Dry matter content and yield of tubers were influenced by all factors in the trial. Later dates of defoliation gave the lowest reducing sugar levels, palest fry colour, highest yield and dry matter content. Increasing the interval from defoliation to harvest reduced dry matter and raised yield. Significant year effects were obtained for dry matter and reducing sugar content.     

糖厂无滤布吸滤机滤汁处理的研究和生产应用

近年来，不少糖厂使用了无滤布真空吸滤机。它的过滤能力大，不用滤布，没有洗滤布水，消除了洗布水对环境的污染。但是，它的滤汁带有大量沉淀物，颜色深，需要回流再次进行澄清处理，对生产有多种不良影响。这个问题关系到糖厂的产品质量、生产能力和环保工作，是一个重要的生产技术问题。     

鄂北棉区麦后移栽棉适宜播期与密度研究

针对鄂北棉区麦后移栽棉生产中存在的播种过早或过迟,种植密度过稀等问题开展的麦后移栽棉的播种期和密度筛选试验。结果表明：鄂北棉区麦后移栽棉的适宜播种期为4月20旨-4月30日,适宜密度为27000～31500株／hm^2。在适宜的播种期和密度下,麦后移栽棉纤维品质符合纺织工业要求。     

Biomass from landscape management of grassland used for biogas production: effects of harvest date and silage additives on feedstock quality and methane yield

Biogas production from grassland biomass harvested during landscape management may help to maintain species‐rich grassland biotopes, but extensive management and late harvests often result in low‐quality biomass. Biogas production from the vegetation of Alopecuretum pratensis, Molinietum caeruleae and Caricetum gracilis, three typical grassland biotopes in north German nature reserves, was investigated in relation to harvest date. In addition, the A. pratensis vegetation was investigated for ensiling and the application of bacterial silage additives. Results indicate that biogas production might be a reasonable utilization pathway for grassland biomass from landscape management if the first cut occurs up to late summer. Methane yields of grassland biomass decreased substantially with later harvest, from up to 309 l_N kg^?1 organic dry matter (ODM) in May to below 60 l_N kg^?1 ODM in February, in correlation with increasing crude fibre contents. Caricetum gracilis vegetation was the least suitable feedstock for biogas production. It showed a rapid decline in methane yields with later harvest and 25% lower methane yields compared with other types of grassland vegetation. Application of silage additives is recommended for adequate preservation of grassland biomass from landscape management by ensiling. Addition of homofermentative lactic acid bacteria improved acidification during ensiling if sufficient fermentable sugar was available. The use of inoculant and molasses enhanced methane yields by 3–55%. Additional carbohydrate source is necessary to ensure proper ensilage when grasses are harvested after late autumn.     

The effect of accumulation period and harvest date in spring on dry-matter yield and forage quality in mixed swards containing Lolium spp. and Trifolium subterraneum in Western Australia

The object of this study was to determine the effect of closing date and date of harvest for conservation (accumulation period), on dry‐matter (DM) yield and forage quality of annual pasture in Western Australia. The field study comprised 48 plots, 2 m × 2 m, sown with either annual ryegrass (Lolium rigidum Gaud.) or Italian ryegrass (L. multiflorum Lam.), and mixed with subterranean clover (Trifolium subterraneum L.). Defoliation of swards until the end of winter was at the three leaves tiller^–1 stage. In spring, once stem nodal development had commenced, swards were defoliated every 3–4 weeks. Swards were defoliated either twice with three leaves tiller^–1 (accumulation period 1 commenced on 15 August); twice with three leaves tiller^–1 and then once after 4 weeks (accumulation period 2 commenced on 11 September); twice with three leaves tiller^–1 and then twice after 4‐week intervals (accumulation period 3 commenced on 9 October) or; twice with 3 leaves tiller^–1 and then twice after 4‐week intervals and then once after 3 weeks (accumulation period 4 commenced on 30 October). From the commencement of the accumulation period, tiller density, DM yield and forage quality were determined weekly for up to 10 weeks. There was a positive quadratic association between DM yield and days after the commencement of the accumulation period. Yields were maximized from accumulation period 1 with 5·3, 6·6 and 9·5 t DM ha^–1, and growth rates were 140, 128 and 145 kg DM ha^–1 d^–1, for Wimmera annual ryegrass and Richmond and Concord cultivars of Italian ryegrass respectively. In contrast, in vitro dry‐matter digestibility (IVDMD) and crude protein (CP) content were negatively associated with days after the commencement of the accumulation period, and initial values were greater than 0·80 and 180 g kg DM^–1 for IVDMD and CP content respectively. The rate of decline in IVDMD d^–1 for Wimmera annual ryegrass was 0·005, 0·019 and 0·012 d^–1 for accumulation periods 1, 2 and 3, respectively, while for Italian ryegrass cultivars Richmond was 0·015, 0·011, 0·02 and 0·012 d^–1 and Concord was 0·014, 0·009, 0·013 and 0·01 d^–1, for the 4 accumulation periods respectively. It is recommended that annual and Italian ryegrass pastures be harvested between 10% and 20% inflorescence emergence when IVDMD will exceed 0·70 regardless of cultivar and/or defoliation practice prior to the commencement of the accumulation period.     

Flowering and true seed production in potato (Solanum tuberosum L.). 1. Effects of inflorescence position,nitrogen treatment,and harvest date of berries

Summary Flowering and true seed production from different order inflorescences in potato (Solanum tuberosum L.) were evaluated in two experiments. The number of flowers per inflorescence, berry set, berry weight, number of seeds per berry and seed weight generally decreased from primary inflorescences to tertiary inflorescences and inflorescences on lateral stems. The possible relation with carbohydrate distribution is discussed. Quality of the seeds produced from the different orders of inflorescences was a function of seed size; larger seeds showed better germination, emergence and seedling growth. Late harvest of berries increased berry weight and number of seeds per berry from primary inflorescences. Application of additional nitrogen during the flowering period did not affect flowering or differences between inflorescence positions in seed production, but it significantly decreased the number of seeds per berry. The practical implications of these results for true seed production are discussed.     

Social Factors Affecting Wetlands Utilization for Agriculture in Nigeria: A case study of sawah rice production

Wetlands have immense poverty-fighting potentials and in Nigeria,more and more people are dependent on wetlands for their livelihoods.To examine the social factors affecting the current status of the wetlands utilization for agriculture in Nigeria,a simple random sampling technique was used to select 200 farmers cultivating wetlands and a structured questionnaire was applied to elicit the information on the social factors.Data collected were described using frequency and percentage and a multiple regression analysis was used to identify significant variables that are determinants of wetland utilization.The results of the analysis showed that significant variables included crop preferences,farming system,culture,taste,land tenure,knowledge of wetland cultivation,perceived suitability,farmers' tribe,location of wetland,and farmers' age.It was concluded with suggestions for the right combination of policies,public awareness,and appropriate farming methods in order to improve wetland utilization in Nigeria.     

A mechanical model for felt in impulse drying: A cellular materials approach. I. Model development and simulation

This paper presents a physically based model of the densification of a felt in the press nip of a paper machine, running at operating conditions similar to those used in impulse drying. The model incorporates the observed features of wet felts compression such as non-linear elasticity and non-recoverable strains that are rate-dependent. A viscoelastoplastic model, based on the cellular solids theory, was developed to describe this behavior. The governing differential equations of the model were established bearing in mind an assembly of modified Maxwell elements combined in series and then arranged in parallel. This approach resulted in a three-dimensional unsteady-state problem, solved by means of an integrator based in the Gear method. The model was used to predict the evolution of thickness, elastic and viscous moduli and apparent density of the material.     

Extraction of rice-planting area and identification of chilling damage by remote sensing technology: a case study of the emerging rice production region in high latitude

Rice is the second largest staple crop in the world and therefore plays an important role in food security. As a thermophilic crop, rice is sensitive to temperature changes. Thus, research on the chilling damage of rice is essential. The Sanjiang Plain is an emerging rice production area and is located at high latitudes in China, the world’s largest rice-producing country. Landsat data were used to extract rice-planting area from 1985 to 2015. MODIS 13Q1, which was uniformly distributed during the growing period of rice, was used to obtain NDVI values of paddies during 2002–2015. Dynamic Identification Index of sterile-type chilling damage and monitoring standard of delayed-type chilling damage were the proposed methods used in this paper, which were used to judge the chilling damage of rice. The results show that in the study region, the rice-planting area in 2015 is nearly 12 times larger than that in 1985. Delayed-type chilling damage occurred in 2002 and 2009, while sterile-type chilling damage occurred in 2005, 2006, 2009, 2010, 2014, and 2015. Comparing with the prevalent meteorological standards, the results indicate that the index and standards proposed in this paper are precise, applicable, and more sensitive than them. The method is a macroscopic and accurate method to identify chilling damage in rice and can also provide a scientific basis to ensuring the stability of rice yield.     

Optimal harvest timing vs. harvesting for animal forage supply: Impacts on production and quality of lucerne on the Loess Plateau,China

The current promotion of larger areas of lucerne (Medicago sativa) production on the Loess Plateau in China prompted this study, which investigated lucerne harvesting practices by farmers and the scope for improved harvest yield and quality by optimizing harvest date, interval and height above ground. On-farm surveys were conducted to document the dominant harvesting practices used by farmers and their perceptions of barriers to adoption of alternative harvesting practices. In districts with less emphasis on livestock, less labour and inadequate facilities to store conserved lucerne, smaller areas of lucerne are grown and it is often harvested daily to meet demand from penned livestock. The consequence is that much of the lucerne is harvested either before or after flowering, resulting in suboptimal yield of biomass and crude protein. Field experiments conducted at low and high rainfall locations on the Loess Plateau over three seasons showed that delaying the start to harvest until after mid-June (the date of first flowering), while not affecting total biomass harvested for the season, does reduce leaf biomass harvested and hence crude protein concentration and yield. Lower crude protein is a consequence of a decline in both leaf percentage in harvested biomass and stem nitrogen concentration. Commencing harvests well before flowering with short (3 week) harvest intervals also penalized total and leaf biomass harvested. Raising cutting height from ground level (current farmer practice) to 50 mm (likely with the advent of mechanized harvesting) did not penalize harvested total or leaf biomass.     

GrazeIn: a model of herbage intake and milk production for grazing dairy cows. 3. Simulations and external validation of the model

GrazeIn is a model for predicting herbage intake and milk production of grazing dairy cows. The objectives of this paper are to test its robustness according to a planned arrangement of grazing and feeding scenarios using a simulation procedure, and to investigate the precision of the predictions from an external validation procedure with independent data. Simulations show that the predicted effects of herbage allowance, herbage mass, herbage digestibility, concentrate supplementation, forage supplementation and daily time at pasture are consistent with current knowledge. The external validation of GrazeIn is investigated from a large dataset of twenty experiments representing 206 grazing herds, from five research centres within Western Europe. On average, mean actual and predicted values are 14·4 and 14·2 kg DM d^?1 for herbage intake and 22·7 and 24·7 kg d^?1 for milk production, respectively. The overall precision of the predictions, estimated by the mean prediction error, are 16% (i.e. 2·3 kg DM d^?1) and 14% (i.e. 3·1 kg d^?1) for herbage intake and milk production, respectively. It is concluded that the GrazeIn model is able to predict variations in herbage intake and milk production of grazing dairy cows in a realistic manner over a wide range of grazing management practices, rendering it suitable as a basis for decision support systems.     

Relation between nitrous oxide production in wetland and groundwater: a case study in the headwater wetland

Wetland is important as a source of nitrous oxide (N₂O), which depends on groundwater and anaerobic conditions involved for denitrification in the aquifer. In order to study the behavior of N₂O in wetland, a typical headwater wetland has been chosen in Ichikawa, Chiba prefecture, Japan. It was found that N₂O fluxes were high at the sides of valley where groundwater flowed in with high concentration of nitrate, and less than 0.045 mg N m^–2 h^–1 in the wetland where groundwater was almost free of nitrite. Also, the concentration of dissolved N₂O in groundwater ranged from 0.78 to 80.5 μg N L^–1 in the study area. Based on the spatial distributions of nitrate, dissolved N₂O, hydraulic head, temperature, dissolved oxygen, and oxidation–reduction potential, etc., it is reasonable to consider that denitrification mainly occurred in the wetland aquifer through which groundwater flowed. Because the concentration of dissolved N₂O was much higher than ambient air, its emission from the water table became the main source of N₂O flux in the study area. The temporal and spatial changes of N₂O flux were strongly affected by the concentration of dissolved N₂O, precipitation and temperature. Finally, the budget of nitrogen in the groundwater was estimated based on the variations of nitrate, the dissolved N₂O and the calculated nitrogen gas along the flow path of groundwater where denitrification was available.     

A simulation model of cereal–legume intercropping systems for semi-arid regions: I. Model development

Cereal–legume intercropping plays an important role in subsistence food production in developing countries, especially in situations of limited water resources. Crop simulation can be used to assess risk for intercrop productivity over time and space. In this study, a simple model for intercropping was developed for cereal and legume growth and yield, under semi-arid conditions. The model is based on radiation interception and use, and incorporates a water stress factor. Total dry matter and yield are functions of photosynthetically active radiation (PAR), the fraction of radiation intercepted and radiation use efficiency (RUE). One of two PAR sub-models was used to estimate PAR from solar radiation; either PAR is 50% of solar radiation or the ratio of PAR to solar radiation (PAR/SR) is a function of the clearness index (K_T). The fraction of radiation intercepted was calculated either based on Beer's Law with crop extinction coefficients (K) from field experiments or from previous reports. RUE was calculated as a function of available soil water to a depth of 900 mm (ASW). Either the soil water balance method or the decay curve approach was used to determine ASW. Thus, two alternatives for each of three factors, i.e., PAR/SR, K and ASW, were considered, giving eight possible models (2 methods × 3 factors). The model calibration and validation were carried out with maize–bean intercropping systems using data collected in a semi-arid region (Bloemfontein, Free State, South Africa) during seven growing seasons (1996/1997–2002/2003). The combination of PAR estimated from the clearness index, a crop extinction coefficient from the field experiment and the decay curve model gave the most reasonable and acceptable result. The intercrop model developed in this study is simple, so this modelling approach can be employed to develop other cereal–legume intercrop models for semi-arid regions.     

Rice crop duration and leaf appearance rate in a variable thermal environment.: I. Development of an empirically based model

Variable crop duration is a major constraint to rice double cropping in arid irrigated environments, such as the Sahel. Photoperiodism and low air and water temperatures during the cool season are the major causes of variability, and cultivars are needed whose photothermal response provides a more stable crop duration. A previous study analyzed cultivar photothermal constants on the basis of progress to flowering. The present study sought to identify, on the basis of leaf appearance rates, the phenological stages that are most sensitive photothermally, and to explore technical options to screen germplasm for stable crop duration. Three Oryza sativa, indica-type rice cultivars (Jaya, IKP, IR64) were sown in the field at 15-day intervals during the dry season of 1995 (11 sowing dates) and 1996 (5 sowing dates) in Ndiaye, Senegal, under full irrigation and wide spacing to reduce microclimate variability. Mean daily water temperature (T_w) varied from 13 to 35°C. After seed soaking, the rate at which the first leaf (L₁) appeared was linearly related with T_w, with a base temperature (T_base) of about 10°C. Appearance rates of the subsequent three leaves (L₂–L₄) had a similar T_base, and presented a distinct temperature optimum (T_opt) at about 23°C, beyond which development rates decreased. Errors were too large to determine differences among cultivars in thermal constants. No significant temperature response was observed for the leaf appearances between L₅ to the flag leaf (L₁₂ to L₂₀). Crop duration to flowering varied by 45 (IR64) and 63 days (Jaya). These variations were associated with highly variable leaf numbers in all cultivars, including photoperiod-insensitive IKP. One-third of the variable duration was hypothesized to be due to a variable basic vegetative phase (BVP), caused by variable germination and leaf appearance rates, and two-thirds to variable duration of panicle induction after BVP. Water temperature was the main determinant of both sources of variability. A simulation model, describing these temperature and photoperiod effects on leaf number, growth duration and leaf appearance rates, was developed using the 1995 data, and satisfactorily validated with the 1996 data. The model was used to identify phenological-stage and cultivar-specific causes of variable crop duration.     

GeneSys-Beet: A model of the effects of cropping systems on gene flow between sugar beet and weed beet

A weedy form of the genus Beta, i.e. Beta vulgaris ssp. vulgaris (hence “weed beet”) frequently found in sugar beet is impossible to eliminate with herbicides because of its genetic proximity to the crop. It is presumed to be the progeny of accidental hybrids between sugar beet (ssp. vulgaris) and wild beet (ssp. maritima), or of sugar beet varieties sensitive to vernalization and sown early in years with late cold spells. In this context, genetically modified (GM) sugar beet varieties tolerant to non-selective herbicides would be interesting to manage weed beet. However, because of the proximity of the weed to the crop, it is highly probable that the herbicide-tolerance transgene would be transmitted to the weed. To evaluate the likelihood of gene flow from GM varieties to weed beet and to propose cropping systems that reduce this likelihood, a model of the effects of cropping systems on population dynamics and gene flow in weed beet was developed, based on the existing spatio-temporal framework GENESYS and on field experiments for parametrising the life-cycle of weed beet. The resulting GENESYS-Beet model consists in simulating every year the life-cycle of weed and crop beet in each field of a given region. During flowering, the various life-cycles connect, leading to pollen exchanges which depend on field areas, shapes and distances. The life-cycle consists of a succession of life-stages for which both densities and genotype proportions are calculated. The relationships between the various stages depend on the crop grown in the field, the stage and genotype of the modelled crop relative, as well as the cultivation techniques (tillage tools and dates, sowing date and density, herbicides, mechanical and manual weeding, harvest date) used to manage the crop. Simulations of GM spread in different farms and regions and of the effects of weed management on the advent of GM beet were carried out to illustrate the possible uses of the model and the consequences of co-existing GM and non-GM crops.     

Influence of cultivar and cutting date on the fatty acid composition of forage crops for grazing beef production in Argentina

The fatty acid composition and total lipids of various forage crops at different cutting dates and seasons, which are used in forage grazing beef production in Argentina, were determined. Three experiments were carried out at the Agricultural Experimental Station of INTA, Anguil, La Pampa, Argentina Samples of alfalfa from three different cultivars with different dormancy groups (G4‐5, G6‐7 and G8‐9) and samples of ryegrasses Bill, Florida and Queue, wheats Charrua and Guapo, and triticale Don Santiago cultivars were taken at different cutting dates and analysed for total lipids and fatty acid composition. Significant differences on the fatty acid composition, the ratios 18:3n‐3/18:2n‐6 and polyunsaturated fatty acids (PUFA) due to cultivar, cutting date and season were found. Taking into account the importance of 18:2n‐6 and 18:3n‐3 fatty acids as substrates for the conjugated isomers of 18:2n‐6 (CLA) and n‐3 PUFA concentrations in beef, the fatty acid composition of forages needs to be considered in forage grazing beef production systems. Data variation in both total lipids and individual fatty acid proportions in forages should be taken into account to establish the potential to cultivate crops for a higher content of n‐3 PUFA and hence the opportunity to deliver more n‐3 PUFA and CLA into beef.     

Environmentally safe and consumer-friendly potato production in the Netherlands. 1. Development of ecologically sound production systems

Summary Methodology is presented for the development of integrated and ecologically based arable farming systems to achieve goals of ecological sustainability and food safety in potato production. The quest for change in potato growing procedures and the need for a quantitative system approach are discussed. Furthermore, the structure of a comprehensive experimental and modelling approach to develop ecologically sound production systems has been outlined. Examples of participatory research projects with farmers are highlighted.     

Vernalization in wheat I. A model based on the interchangeability of plant age and vernalization duration

Vernalization treatments of 0 to 70 d initiated when 0 to 8 leaf tips were visible were applied to plants of the winter wheat (Triticum aestivum L.) cultivars Pioneer 2548 and Augusta. All plants headed irrespective of duration of vernalization. Unvernalized plants of Pioneer 2548 and Augusta had mean final leaf numbers (FLN) of 20.8 ± 1.3 and 21.7 ± 1.0, respectively. Increased duration of vernalization generally reduced FLN within an age treatment until an age-dependent point of vernalization insensitivity was reached. Estimates of the minimum days of vernalization required to reach vernalization insensitivity decreased in a linear fashion as plant age at the onset of vernalization treatment increased. The number of leaves appearing after the onset of vernalization insensitivity averaged 6.3 ± 0.5. FLN minus six appears to be a valid estimate in our experimental conditions for the onset of vernalization insensitivity, at least for plants that had six or more leaves appearing after the end of vernalization treatment. Linear regressions of FLN minus six against days of vernalization were significant for both cultivars (for treatments with six or more leaves emerging after vernalization). The Y-intercepts of the fitted regressions were close to values obtained by subtracting six from FLN of unvernalized plants. Both intercept and slope were controlled genetically. Accumulated plant age, expressed as leaf stage, enables attainment of vernalization insensitivity, independent of, or in combination with vernalization treatment.