Availability and use of feed resources in crop–animal systems in Asia

Feed resources and nutrition constitute the principal technical constraints to ruminant production in Asia. Four main categories of feed resources are potentially available for use in smallholder crop–animal systems. These are pastures (native and improved grasses, herbaceous legumes and multi-purpose trees), crop residues, agro-industrial by-products (AIBPs), and non-conventional feed resources (NCFRs). Priorities for the use of crop residues in terms of nutrient potential and animal species are indicated. Of the technologies developed to improve the nutritive value of crop residues, more attention has been given to chemical treatment of cereal straws than to supplementation. However, a failure to demonstrate cost-effectiveness has discouraged on-farm adoption. The production of fodder from food crop systems and the establishment of multi-purpose trees and shrubs are potentially important for insuring adequate feed supplies for ruminants and improving soil fertility, but there has been limited adoption on small farms to date. Equally, there is significant potential for the more effective use of locally-produced AIBPs and NCFRs, all of which are under-utilised currently.     

Annual forecasting of the Australian macadamia crop – integrating tree census data with statistical climate-adjustment models

To facilitate marketing and export, the Australian macadamia industry requires accurate crop forecasts. Each year, two levels of crop predictions are produced for this industry. The first is an overall longer-term forecast based on tree census data of growers in the Australian Macadamia Society (AMS). This data set currently accounts for around 70% of total production, and is supplemented by our best estimates of non-AMS orchards. Given these total tree numbers, average yields per tree are needed to complete the long-term forecasts. Yields from regional variety trials were initially used, but were found to be consistently higher than the average yields that growers were obtaining. Hence, a statistical model was developed using growers’ historical yields, also taken from the AMS database. This model accounted for the effects of tree age, variety, year, region and tree spacing, and explained 65% of the total variation in the yield per tree data. The second level of crop prediction is an annual climate adjustment of these overall long-term estimates, taking into account the expected effects on production of the previous year’s climate. This adjustment is based on relative historical yields, measured as the percentage deviance between expected and actual production. The dominant climatic variables are observed temperature, evaporation, solar radiation and modelled water stress. Initially, a number of alternate statistical models showed good agreement within the historical data, with jack-knife cross-validation R² values of 96% or better. However, forecasts varied quite widely between these alternate models. Exploratory multivariate analyses and nearest-neighbour methods were used to investigate these differences. For 2001–2003, the overall forecasts were in the right direction (when compared with the long-term expected values), but were over-estimates. In 2004 the forecast was well under the observed production, and in 2005 the revised models produced a forecast within 5.1% of the actual production. Over the first five years of forecasting, the absolute deviance for the climate-adjustment models averaged 10.1%, just outside the targeted objective of 10%.     

Forage options for smallholder crop–animal systems in Southeast Asia: working with farmers to find solutions

Most research and development involving forages in Southeast Asia has been directed towards impacts in commercial farming systems. Little adoption of forages has occurred in smallholder livestock systems, which account for the vast majority of the livestock in the region. The main reason for this lack of adoption is the linear processes that have been used to develop forage technologies on research stations leading to the extension of ‘finished' technology packages. This paper describes existing uses of forages in Southeast Asian farming systems and, using a recent case study, describes the potential for developing smallholder forage systems using participatory approaches to technology development.     

Resource-centred thinking in river basins; should we revoke the crop water requirement approach to irrigation planning?

The paper examines the method of using project irrigation requirements (PIR) in the design and rehabilitation of small-scale smallholder irrigation systems within multi-sector and dynamic river basins. This procedure, which employs equations that determine irrigation and crop water requirements, is found embedded in irrigation thinking and planning methodologies throughout the irrigation world. The paper argues that if the PIR equations are used formally and conventionally without sufficiently accounting for changing demands for water in semi-arid river basins, they can lead to irrigation designs that over-prioritise water for individual irrigation systems and as such be labelled ‘irrigation-centred’. Although other adjustments and attempts at re-allocating water might be undertaken, basin managers are often unable to recognise, accommodate or transcend the irrigation focus that this approach generates thus curtailing the efficacy of re-allocation efforts. This argument is made on the basis of observations in the Usangu Plains of Tanzania of farmer-originated irrigation and donor attempts at rehabilitation and modernisation. Features of a modified planning and design methodology are suggested, which considers irrigation alongside other water sectors, and focuses on the river basin rather than on the individual system; an alternative which, it is proposed, is more flexible and ‘water-resource-centred’. The implications of this dualism in approaches (irrigation-centred or resource-centred) for basin management, livelihoods, conflict mediation and formal irrigation rehabilitation projects are explored.     

The origin and hazard of inputs to crop protection in organic farming systems: are they sustainable?

Sustainability is defined as the ability of a system to ‘continue’. In view of this definition, several aspects of the crop protection activity in organic farming are reviewed according to their ability to ‘continue’. As no absolute measure of sustainability is available, this analysis takes the form of a comparison between organic and conventional crop protection methods. Two elements of crop protection are considered: one being the source of the inputs to crop protection and the other being the environmental hazard of the chemicals used in crop protection. In addition, the sustainability of some of the wider issues related to crop protection methods in organic farming are discussed. It is concluded that organic farming systems are not sustainable in the strictest sense. Considerable amounts of energy are input to organic farming systems, the majority of the compounds utilised in crop protection are derived from non-renewable sources and incur processing and transport costs prior to application. Further, these compounds are not without toxicological hazards to ecology or humans. Despite these problems, it is concluded that organic farming is probably more sustainable than conventional farming in a bio-physical sense. However, an assessment of the overall sustainability of farming systems may depend upon the valuation given by society to their inputs and outputs, and in this sense it is extremely difficult to assess which farming system is most sustainable.     

A GIS-based approach for up-scaling capillary rise from field to system level under soil–crop–groundwater mix

Capillary rise represents an often neglected fraction of the water budget that contributes to crop water demand in situations of shallow groundwater levels. Such a situation is typical in irrigated areas of Central Asia where water from capillary rise is exploited by farmers to meet production targets in Uzbekistan under uncertain water supply. This leads to higher water inputs than needed and creates a vicious cycle of salinization that ultimately degrades the agricultural land. In this study, capillary rise is quantified at different spatial scales in the Shomakhulum Water Users Association (WUA), situated in the southwest of Khorezm, Uzbekistan. The mathematical model HYDRUS-1D was used to compute the capillary rise at field level for three major crops (cotton, wheat and vegetables) on six different hydrological response units (HRUs). These six HRUs having homogenous groundwater levels (1–2 m beneath the soil surface) and soil texture were created using GIS and remote-sensing techniques. Capillary rise from these HRU was then up-scaled to WUA level using a simple aggregation approach. The groundwater levels simulated by FEFLOW-3D model for these HRUs in a parallel study under four improved irrigation efficiency scenarios (S-A: current irrigation efficiency or business-as-usual, S-B: improved conveyance efficiency, S-C: increased application efficiency and S-D: improved conveyance and application efficiency) were then introduced into HYDRUS-1D to quantify the impact of improved efficiencies on the capillary rise contribution. Results show that the HRUs with shallow groundwater-silt loam (S-SL), medium groundwater-silt loam (M-SL) and deep groundwater-silty clay loam (D-SCL) have capillary rise contribution of 28, 23 and 16 % of the cotton water requirements, 12, 5 and 0 % of the vegetable water requirements and 9, 6 and 0 % for the wheat water requirements, respectively. Results of the scenarios for the whole WUA show that the maximum capillary rise contribution (19 %) to the average of all crops in the WUA was for the S-A scenario, which reduced to 17, 11 and 9 % for S-B, S-C and S-D, respectively. Therefore, it is recommended that before any surface water intervention or drainage re-design, water managers should be informed about the impacts on groundwater hydrology and hence should adopt appropriate strategies.     

Determining water–yield relationship,water use efficiency,crop and pan coefficients for silage maize in a semiarid region

A field study was conducted to determine effects of seasonal deficit irrigation on plant cob, leaf, stem and total fresh yield, plant height and water use efficiency (WUE) of silage maize for a 2-year period in the semiarid region. In addition, the crop and pan coefficients k _c and k _p of silage maize were determined in full irrigation conditions. Irrigations were applied when approximately 50% of the usable soil moisture was consumed in the effective rooting depth at the full irrigation treatment. In deficit irrigation treatments, irrigations were applied at the rates of 80, 60, 40, 20 and 0% of full irrigation treatment on the same day. Irrigation water was applied by hose-drawn traveler with a line of sprinklers. Increasing water deficits resulted in a relatively lower cob, leaf, stem and total fresh yields. The linear relationship between evapotranspiration and total fresh yield were obtained. Similarly, WUE was the highest in full irrigation conditions and the lowest in continuous stress conditions. According to the averaged values of 2 years, yield response factor (k _y) was 1.51 for silage maize. When combined values of 2 years, seasonal pan coefficient (k _p) and seasonal crop coefficient (k _c) were determined as 0.84 and as 1.01 for silage maize, respectively.     

Measured and estimated water use and crop coefficients of grapevines trained to overhead trellis systems in California’s San Joaquin Valley

The use of overhead trellis systems for the production of dry-on-vine (DOV) raisins and table grapes in California is expanding. Studies were conducted from 2006 to 2009 using Thompson Seedless grapevines grown in a weighing lysimeter trained to an overhead arbor trellis and farmed as DOV raisins for the first two years and for use as table grapes thereafter. Maximum canopy coverage for the two lysimeter vines across years was in excess of 80 %. Seasonal (15 March–31 October) evapotranspiration for the lysimeter vines (ET_Lys) was 952 mm in 2007 (farmed as DOV raisins) and 943 and 952 mm (when farmed as table grapes). The maximum crop coefficient (K _cLys) across all 4 years ranged from 1.3 to 1.4. These maximum values were similar to those estimated using the relationship where K _c is a function of the amount of shaded area measured beneath the canopy at solar noon (K _c = 0.017 × percent shaded area). Covering the lysimeter’s soil surface with plastic (and then removing it) numerous times during the 2009 growing season (1 June–14 September) reduced ET_Lys from an average of 6.4 to 5.6 mm day^?1 and the K _c from 1.07 to 0.93. A seasonal basal K _c (K _cb) was calculated for grapevines using an overhead trellis system with a 13 % reduction in the K _cLys across the growing season.     

Assessment of the parameters of a mechanistic soil–crop–nitrogen simulation model using historic data of experimental field sites in Belgium

Intensification of the agricultural sector and the increase in quantity and decrease in quality of municipal and industrial wastewater, in particular during the past decades, resulted in many industrial countries, such as Belgium, in a sharp degradation of surface water and groundwater. To control the current degree of contamination and reduce the environmental impact of the agricultural sector, the Flemish government recently introduced a number of regulations aiming at controlling the use of nitrogen fertilisers. To facilitate the implementation and the control of the new regulations, threshold values of allowable doses of organic and inorganic nitrogen fertilisers, and their spreading in time were made soil independent. As the soil physical, chemical and biological response depends on the geohydrology of the site and the past fertilisation practice, fertiliser standards applied on different soil–crop systems result in different leaching patterns.To assess the effect of the soil on the nitrogen leaching, a number of past experimental field trials were analysed using the WAVE model as modelling tool for the reconstruction of the nitrogen dynamics. As a first step in the study, the historic data of the field experiments were used to calibrate and validate the WAVE model. The deterministic calibration and validation of the WAVE model yielded a set of model parameters for the examined soil–crop–fertiliser practice conditions. The bottlenecks in the calibration were the nitrogen mineralisation parameters and the initialisation and subdivision of the soil organic matter over the different organic pools. The model validation, being the second step in the study, revealed the power of the WAVE model to predict the evolution and transformations of nitrogen in the soil profile and the leaching of nitrate at the bottom of the root zone. In a third step, the WAVE model was used in a scenario-analysis exercise to examine the factors effecting the amount of nitrate leached at the bottom of the root zone. This analysis revealed that the nitrate leached out of the soil profile is controlled by the fertiliser practice, the rainfall depth and its distribution, the soil texture, the soil mineralisation capacity and the past fertilisation practice.     

The effects of crop load and irrigation rate in the oil accumulation stage on oil yield and water relations of ‘Koroneiki’ olives

The interactions between irrigation rates applied during the oil accumulation stage and crop load were studied in a six-year-old very-high-density Koroneiki (Olea europaea L.) orchard. Five irrigation rates, determined as thresholds of midday stem water potential, were applied from July 1st until harvest in 2008 and 2009 and from July 1st to the end of September in 2010. Oil yield increased with increasing crop load in all the irrigation treatments. Oil yield did not respond to increasing irrigation at very low crop load and the higher the crop load the higher the response to irrigation. There was no response to irrigation at the lowest crop loads, but the higher the irrigation rate the higher the oil yield at high crop loads. The predicted commercial oil yield at common fruit counts increased from 1.99 t/ha at the lowest irrigation rate to 3.06 t/ha at the highest irrigation rate. Stomatal conductance decreased with decreasing stem water potential but leveled off at 30–60 mmol m^?2 s^?1 at stem water potential values lower than ?4.0 MPa. High crop load increased stomatal conductance and decreased stem water potential relative to low crop load at low and medium irrigation rates. The effect of crop load on water relations became evident by the end of August and was well pronounced at the beginning of October. Physiological and irrigation water management implications related to the interactions between tree water status and crop load are discussed.     

Determination of the crop coefficient for grafted ‘Tahiti’ lime trees and soil evaporation coefficient of Rhodic Kandiudalf clay soil in Sao Paulo,Brazil

The expansion of permanent trickle irrigation systems in Sao Paulo (Brazil) citrus has changed the focus of irrigation scheduling from determining irrigation timing to quantifying irrigation amounts. The water requirements of citrus orchards are difficult to estimate, since they are influenced by heterogeneous factors such as age, planting density and irrigation system. In this study, we estimated the water requirements of young ‘Tahiti’ lime orchards, considering the independent contributions from soil evaporation and crop transpiration by splitting the crop coefficient (Kc = ETc/ETo) into two separate coefficients; Ke, a soil evaporation coefficient and Kcb, a crop transpiration coefficient. Hence, the water requirement in young ‘Tahiti’ lime (ET_y) is ET_y = (Ke + Kcb) · ETo, where ETo is the reference crop evapotranspiration. Mature tree water requirement (ET_m) is ET_m = Kcb · ETo, assuming no soil water evaporation. Two lysimeters were used; one was 1.6 m in diameter and 0.7 m deep, and the other was 2.7 m in diameter and 0.8-m deep. The first one was used to calculate evaporation and the second one was used for transpiration. ETo was estimated by the Penman–Monteith method (FAO-56). The measurements were conducted during a period between August 2002 and April 2005 in Piracicaba, Sao Paulo state, Brazil. The lysimeters were installed at the center of a 1.0-ha plot planted with ‘Tahiti’ lime trees grafted on ‘Swingle’ citrumelo rootstock. The trees were 1-year old at planting, spaced 7 × 4 m, and were irrigated by a drip irrigation system. During the study period, Kc varied between 0.6 and 1.22, and Kcb varied between 0.4 and 1.0. The results suggested that for young lime trees, the volume of water per tree calculated by Ke + Kcb is about 80% higher than the volume calculated using Kc. For mature trees, the volume of water per tree calculated using just Kcb can be 10% less than using Kc. The independent influence of soil evaporation and transpiration is important to better understand the water consumption of young lime trees during growth compared to mature lime trees.     

Using the DRAINMOD-N model to study effects of drainage system design and management on crop productivity,profitability and NO3–N losses in drainage water

The environmental impacts of agricultural drainage have become a critical issue. There is a need to design and manage drainage and related water table control systems to satisfy both crop production and water quality objectives. The model DRAINMOD-N was used to study long-term effects of drainage system design and management on crop production, profitability, and nitrogen losses in two poorly drained soils typical of eastern North Carolina (NC), USA. Simulations were conducted for a 20-yr period (1971–1990) of continuous corn production at Plymouth, NC. The design scenarios evaluated consisted of three drain depths (0.75, 1.0, and 1.25 m), ten drain spacings (10, 15, 20, 25, 30, 40, 50, 60, 80, and 100 m), and two surface conditions (0.5 and 2.5 cm depressional storage). The management treatments included conventional drainage, controlled drainage during the summer season and controlled drainage during both the summer and winter seasons. Maximum profits for both soils were predicted for a 1.25 m drain depth and poor surface drainage (2.5 cm depressional storage). The optimum spacings were 40 and 20 m for the Portsmouth and Tomotley soils, respectively. These systems however would not be optimum from the water quality perspective. If the water quality objective is of equal importance to the productivity objective, the drainage systems need to be designed and managed to reduce NO₃–N losses while still providing an acceptable profit from the crop. Simulated results showed NO₃–N losses can be substantially reduced by decreasing drain depth, improving surface drainage, and using controlled drainage. Within this context, NO₃–N losses can be reduced by providing only the minimum subsurface drainage intensity required for production, by designing drainage systems to fit soil properties, and by using controlled drainage during periods when maximum drainage is not needed for production. The simulation results have demonstrated the applicability of DRAINMOD-N for quantifying effects of drainage design and management combinations on profits from agricultural crops and on losses of NO₃–N to the environment for specific crop, soil and climatic conditions. Thus, the model can be used to guide design and management decisions for satisfying both productivity and environmental objectives and assessing the costs and benefits of alternative choices to each set of objectives.     

Effects of the measures envisaged in “Agenda 2000” on arable crop producers and beef and veal producers: an application of Positive Mathematical Programming to representative farms of a Spanish region

The authors analyse the possible effects of the measures envisaged in “Agenda 2000”, approved by the Berlin European Council of March 1999, on representative farms specialised in arable crop production and beef and veal production. Three economic sizes are considered for each of these types of farming (4–16 European Size Units [ESU], 16–40 ESU and >40 ESU). The analysis is made by means of Positive Mathematical Programming, utilising quadratic cost functions. The results show that the increase in compensatory payments and premiums would not offset a possible decrease in market prices, and therefore, for most of the agricultural holdings studied, the economic results worsen. It is worth noting that the total subsidies share in agricultural incomes is notably increased.