Effect of Different N Nutrient Contents on Biomass of Green Manure as Second Crop, Under Unfavorable Climate Conditions in Hungary

Abstract

Abstract. The growth and nutrient composition of three plant species produced as second crop for green manure purposes (phacelia -Phacelia tanacetifolia Benth., mustard -Sinapis alba L. and oilseed radishRaphanus sativus L. var. oleiformis Pers.) were studied between 2007 and 2011 at the Crop Production and Biomass Utilisation Demonstration Centre (Növénytermesztési és Biomassza-hasznosítási Bemutató Központ) of Szent István University under unfavourable site conditions on Luvic Kastanozems soil (WRB 2014), subject to two different levels of fertiliser supply (0 kg/ha N; 50 kg/ha N). The application of 50 kg/ha nitrogen active ingredient multiplied the biomass of each of the three plant species -as an average of the five years of the study to 2.86, 3.07 times and 2.51 times the amount produced without treatment, in the case of phacelia, mustard and oilseed radish, respectively. The rates of the increase of the dry matter content were somewhat lower than those of the green mass increase because the nitrogen improved supply also resulted in an increase in the water content of the green manure plants. One kilogram per hectare added nitrogen increased the green mass and the dry matter content by 412.5 kg and by 37.9 kg as an average of the five years of the study in the case of phacelia, while in the case of mustard the green mass and the dry matter content increased by 431.4 kg and 59.1 kg, respectively. In the case of oilseed radish the corresponding figures were 386.7 kg and 34.1 kg, respectively. Without added nitrogen however, the generally acceptable 10 t/ha biomass could not always be harvested from the given site of relatively unfavourable conditions. The amount of NPK absorbed per hectare also increased in response to the added nitrogen -to 2.60/2.36/2.13 times the in the case of phacelia over [2007][2008][2009][2010][2011]2.81/2.29/2.29 times in the case of mustard and 2.72/2.09/1.95 times in the case of oilseed radish. Each kilogram of added nitrogen enabled the uptake of an added amount of 1.6 kg, 2.3 kg and 1.8 kg of additional nitrogen in the case of phacelia, mustard and oilseed radish, respectively, as an average of the period between 2007 and 2011. The nitrogen applied made a significant contribution to the uptake of phosphorous and potassium as well. Each kilogram of added nitrogen increased the uptake of P 2 O 5 by 0.5 kg. 0.5 kg and 0.6 kg in the case of phacelia, mustard and oilseed radish, respectively and it boosted the uptake of K 2 O by 1.8 kg, 2.1 kg and 1.4 kg in the case of phacelia, mustard and oilseed radish, respectively. It may be concluded from the above results that when a second crop is grown for use as green manure at the given cropping site the application of nitrogen is always recommended, to the extent possible, but if the straw is left on the soil surface after cereals, it is definitely strongly recommended.