The paper discusses the contribution of crop residues (CR) to feed resources in the context of the water productivity of CR in livestock feeding, using India as an example. It is argued that crop residues are already the single most important feed resource in many livestock production systems in developing countries and that increasing their contribution to livestock feeding needs to be linked to improving their fodder quality. Using examples from multi-dimensional crop improvement, it is shown that CR fodder quality of key crops such as sorghum, rice and groundnut can be improved by genetic enhancement without detriment to grain and pod yields. Improving crop residue quality through genetic enhancement, agronomic and management interventions and strategic supplementation could improve water productivity of farms and systems considerably. The draw-backs of CR based feeding regimes are also pointed out, namely that they result in only moderate levels of livestock productivity and produce higher greenhouse gas emissions than are observed under feeding regimes that are based on high quality forages and concentrates. It is argued that feed metabolisable energy (ME) content should be used as an important determinant of livestock productivity; water requirement for feed and fodder production should be related to a unit of feed ME rather than feed bulk. The paper also revisits data from the International Water Management Institute (IWMI) work on livestock-water productivity in the Indian state of Gujarat, showing that water input per unit ME can vary several-fold in the same feed depending on where the feed is produced. Thus, the production of one mega joule of ME from alfalfa required 12.9L of irrigation-derived water in south Gujarat but 50.7L of irrigation-derived water in north Gujarat. Wheat straw in south Gujarat required 20.9L of irrigation-derived water for 1MJME and was in this instance less water use efficient than alfalfa. We conclude that water use efficiency across feed and fodder classes (for example crop residue v. planted forages) and within a feed is highly variable. Feeding recommendations should be made according to specific water use requirement per unit ME in a defined production system.

Climate change will not only affect crop biomass production but also crop quality. While increasing atmospheric CO2 concentrations are known to enhance photosynthesis and biomass production, effects on the chemical composition of plants are less well known. This is particularly true for major crop plants with respect to harvestable yield quality. Moreover, it remains open, how these effects on quality may be realized under field conditions and how management (e.g. plant N nutrition) or environmental factors (e.g. water availability) will alter impacts of elevated CO2. Here we report on a series of free air CO2 enrichment (FACE) experiments with wheat and barley and with maize in which effects of elevated CO2 combined with different levels of N supply (wheat and barley) and with drought stress (maize) on grain and biomass quality characteristics were investigated. Winter wheat and winter barley (1st experiment) and maize (2nd experiment) were grown in the field each for two growing seasons under ambient and elevated CO2 concentration (FACE, 550μmol mol-1). Wheat and barley were grown under adequate N supply and under 50% of adequate N as sub-treatments. In the maize experiment rain shelters were used to create two different levels of plant water supply (well-watered and drought stress – about 50% of well-watered) as sub-treatments. Treatment effects on elemental composition and a variety of quality characteristics of the plant material at final harvest were investigated. This included a detailed analysis of wheat grain protein components and of different fiber fractions of maize. Compiled results of the relative effects of elevated CO2, N and drought stress treatments on different quality parameters of the crops are presented.

This study sets out to measure CWU (litre/kg ECM, energy-corrected milk) of typical milk production systems in 60 dairy regions from 49 countries representing 85% of the world׳s milk production. The extended version of TIPI-CAL 5.2 including water model was used for data analysis.The results have shown the CWU/kg ECM ranged between 739L on the Danish farm to 5622 l on the Ugandan farm with a global average of 1833L. When looking at averages per region, the CWU was lowest in Europe (913L) and highest in Africa (3384L) with large intra- and inter-regional differences. Compared with grazing and intensive production system, low yielding cows on small-scale farms have the highest CWU/kg ECM. The key driver for variation in CWU/kg ECM is feed, accounting for 94–99% of the total CWU. Increasing milk productivity might be one of the promising ways to reduce CWU/kg ECM. However, this might also lead to the negative impact into water supply systems if this increase is dependent on land irrigation in water scarce areas. The findings of this study showed the need to address the location of the farm, the feed quality, feeding system and milk production intensity simultaneously when aiming at efficient water resource management which would help to contribute food production and livelihood security of dairy farmers worldwide.