Steady state nutrition by transpiration controlled nutrient supply

Programmed nutrient addition with a constant relative addition rate has been advocated as a suitable research technique for inducing steady state nutrition in exponentially growing plants. Transpiration controlled nutrient supply is proposed as an alternative technique for plants with a short or no exponential growth phase. A two-weeks experiment with transpiration controlled nitrogen supply to Pennisetum americanum was carried out to evaluate this method. After an adaptation phase a constant plant N-concentration was maintained, while the relative growth rate decreased rapidly. The transpiration coefficient was almost constant in time and insensitive to moderate N-stress, but increased sharply when plant N-concentration dropped below 1760 mmol/kg DW. Relative growth rate and nitrogen productivity showed a steep decline at the lowest N concentrations (about 1000 mmol/kg DW). Nitrogen productivity was optimal at about 1760 mmol/kg DW. The results show that transpiration controlled nutrient supply is applicable in research and gives accurate results in growth analysis. When the transpiration coefficient is known, the nutrient solution can be adjusted to give any desired plant N-concentration, except for the lowest concentrations

Effects of climate change on the yield and financial returns of arable crops and grassland in the Netherlands

Abstract niet beschikbaarUsing simulation models in combination with results of "Open Top Chamber" experiments, the potential effect of climate change on the yield of arable crops and grassland in the Netherlands was estimated. The changes in atmospheric CO2 concentration and temperature were derived from two baseline scenarios with estimated atmospheric CO2 concentrations of 425 or 438 vpm in the year 2020 and 512 or 566 vpm in 2050, for a low and a high scenario respectively. In these scenarios, temperature increased by 1.5 or 1.6 _C in 2020 and 3.0 or 3.5 _C in 2050. The temporal and spatial distribution of the precipitation were affected by global change but the yearly total remained equal. Predictions of changes in yield were made using simulation models of the LINTUL-type. These model shave been applied for land use evaluation, e.g. to assess the production potentials of new cropping areas in dependence of climatic conditions and availability of water and fertilizer. The predicted yields increased in the range between 19% to 50% (grassland), 16% to 35 % (sugar beet), 7% to 32 % (potato), 4% to 8% (winter wheat), but declined for Maize (-7 to -16%). Translated to monetary effects for the producer, the effects are slightly negative, due to lower price expectations and changes in land use. The net financial losses range from -11 million guilders for potato to -158 million guilders for cereals. Other crops are within this range with the exception of positive financial return for grasslands from 266 million guilder in 2020 to 334 million guilder in 2050. The financial effects for the consumer are small: a benefit of 130 to 150 million guilder for potato due to lower prices and zero effects for all other crops. Considering the limitations of the study, which are described and discussed, it can be concluded that the predicted overall effects of climate change on Dutch agriculture will be small.RIV