1 Introduction
    The handbook offers a broad spectrum of rapid field tests covering the chemical analysis of water, soil and plant samples. The presented tests focus on the determination of parameters required to evaluate crop growth especially under saline growth conditions. Experts involved practically in the management of irrigated, salt-affected agriculture are aware of the fact that the chemical analysis of salinity parameter usually does not cover all required information for a satisfying evaluation. A professional evaluation of salt-affected sites also needs reliable data on supplemental soil fertility factors. In order to correspond to the complexity of fertility problems related to saline sites, the HANDBOOK offers numerous approaches to determine fertility factors to complete the picture. Table 1 gives an overview of the full measuring programme presented in this HANDBOOK and feasible with the portable field laboratory 'SALINITY AND SOIL FERTILITY KIT'.
    Tab. 1: Full Test - Programme of the Field Laboratory
    Water Soil Plant
    • EC and Total Salt conc.
    • pH and HCO³
    • NO³ and high K
    • Cl- and SO4
    • Ca and Mg
    • Gypsum
    • Osmot. Effect. Salinity
    • Na and SAR, ESP
    • RSC and adjR-Na
    • Mg-adj. SAR
    • pH (H²O and CaCl²)
    • EC and %o salt
    • Cl- and diss. SO4
    • dissolved Ca, Mg, Na
    • Gypsum: dissolv., pecip.
    • Effective Salinity
    • SAR, ESP, Mg-adjESP
    • pH-KCl and CEC
    • Exchangeable Ca, Mg
    • Plant-available N, P, K
    • Carbonate and OM
    • Nitrate
    • Phosphate
    • Potassium
    For those readers, who are experienced with field and laboratory work in developing countries, the advantage of a compact and portable field lab covering a wide range of determinations will be principally clear. The field lab offers a significant potential to improve quality of field studies and to increase working efficiency.
    But for those who may believe that the application of a 'low input technology' as this field lab requires co-workers of lower qualification or formation, I must warn from the beginning. From my own experience I want to stress, that the practical execution of most methods is simple and will be no problem. However a qualified evaluation of data often requires a specific experience formation in order to avoid misuse or misinterpretation and to profit as soon as possible from the potential of rapid field methods.
    The HANDBOOK covers a wide range analytical procedures and data evaluation, which is required for extended studies at the start of a project, when little or nothing is known on the resources and the project environment. In cases where specific site factors were already identified as critical there is no need to apply the full measuring programme. The measuring programme can focus on the most critical site factors. This aspect will certainly encourage those, who are confused from the large measuring programme offered in this HANDBOOK.
    Consequently my recommendation for the efficient application of the rapid field tests within projects is to progress in two steps:

    • In the first phase, when site conditions or project environment are still unknown and there is no or little experience with application of rapid field tests, an expert specialized in rapid chemical tests and their evaluation has to be engaged. Part of his job will be to identify the most relevant plant growth limiting site factors in close cooperation with local/national experts, another part will be to train local experts in the application of rapid test required under the special site conditions.

    • The second phase starts, when the most important critical factors are known. The local experts are well experienced in the application of the identified rapid field tests and their evaluation. Based on this progress of the first phase and the identified need for analytical methods a small manual/report focussing on local need is prepared. If required the composition of the test-kits in the field lab can be adapted to the identified measuring programme. There is no urgent need for a permanent cooperation with the specialist, but it is recommended to stay in contact by reporting and occasional visits and discussions.

    Due to didactic reasons the HANDBOOK starts with the analysis and evaluation of water samples. From experience we know that the beginner will have little problems with the practical analysis and evaluation of water samples. The experience gained with the analysis of water samples will facilitate the user to analyse soil samples.
    In order to limit the volume of the HANDBOOK the description of the analytical procedures will not repeat all technical details that are already presented in the instructions of the specific test-kits. These technical details must be taken from the directions found in the specific kits.
    After use all chemical flasks have to be closed carefully in order to avoid losses by evaporation and leaking. It is recommanded to place all liquid filled bottles in the direction of the handle of the set. The set should not be exposed for a longer period to high sun irridation and high temperatures, as the decay of some chemicals is accelerated.
    Principally all analytical procedures can be carried out directly at the site of the sampling. But for routine analysis of greater series it is recommanded to install the field lab in a cottage or simple house and to transport the samples to this location.

    The HANDBOOK offers many tables and graphs recommended for a quantitative data evaluation. Many critical ranges are considered as relatively 'safe', some may be questionable or tentative. The limited reliability of some data and their evaluation can be improved significantly, when a cross-check of different approaches is carried out (e.g. comparison of soil and plant data, visual impressions). I admit you may also meet situations, where the critical ranges offered in the HANDBOOK appear unsatisfactory, which reflects the world-wide very different site conditions. The critical ranges may only serve as a very first and rough approximation, but even this is usually better than nothing. In such cases you are cordially invited to coorperate with me and to adapt the recommended classifications. For long-term monitoring programmes an adaptation to local conditions is required anyhow.
    Concerning the evaluation of water-soluble Magnesium in irrigation waters and soils I propose a new approach. This appeared necessary to my own practical experience, but also to the contradictory evaluation of Mg in classical evaluation proposals for Mg in waters (SAR after USDA) and soils with respect to soil physical properties. The classical SAR assumes positive Mg-effects on soils physical properties, but many soil scientists have proved that high exchangeable Mg-percentages may have a very unfavourable affect on soil physical parameters.

    In some respects the HANDBOOK exceeds its primary objective to support the professional evaluation and management of salt-affected crop production:

    • Chapter 3.6.8 addresses to the controversially discussed problem of root water uptake under saline soil conditions. I have severe doubts that root water uptake can be evaluated from a simple function, where soil matric and osmotic water potential are simply additive and equal in this respect.

    • Chapter 3.6.11 presents a concept for future research needed for further progress in saline irrigation, where the horizontal distribution of salts in the rhizosphere during irrigation cycles and the effect of root morphology play a central role for crop salt tolerance.

    Last not least I hope to receive your comments on this HANDBOOK, the proposed methods and evaluations, especially when you have constructive proposals that may contribute to an improvement. I am 100% sure that there are many things to correct and to add. I will be very glad to learn from your experience.