Winter cover crops may provide different environmental benefits in agricultural systems. The aim of this study was to determine the effect of cover crops used as green manure on the soil nitrogen (N) budget and yield of silage maize (Zea mays L.). A field experiment was conducted between 2011 and 2013 at three locations in Vojvodina Province, Serbia. It compared common vetch (Vicia sativa L.), triticale (× Triticosecale Wittm. ex A. Camus), their mixture grown as cover crops, N fertilisation at two doses (N1 and N2), and an unfertilised fallow as a control. Cover crops were sown in autumn 2011 and 2012 and were ploughed in during May of the year after which silage maize was sown. Results show that the ability of cover crops to provide benefit for a subsequent crop is highly related to weather conditions, mainly precipitation. The two years of the study experienced completely different weather conditions, showing two aspects of how cover crops can affect subsequent crop yield and amount of N left in the soil. In 2012, the N budget was higher in all three cover crops at all locations than N1 and the control because of unfavourable weather conditions for mineralisation of organic matter. However, the cover crops had a negative effect on silage maize yield. In 2013 (an average year), the N budget was significantly higher after cover crops, and was followed by a higher yield of silage maize. Based on the 2-year average, the highest value of apparent N remaining in the soil was recorded in the mixture treatment (288.13 kg N ha–1); treatments with vetch and triticale had approximately equal values (272.17 and 272.71 kg N ha–1). The N fertilisation treatments and the control had significantly lower average values of residual N.

Legumes and brassicas have much in common: importance in agricultural history, rich biodiversity, numerous forms of use, high adaptability to diverse farming designs, and various non-food applications. Rare available resources demonstrate intercropping legumes and brassicas as beneficial to both, especially for the latter, profiting from better nitrogen nutrition. Our team aimed at designing a scheme of the intercrops of autumn- and spring-sown annual legumes with brassicas for ruminant feeding and green manure, and has carried out a set of field trials in a temperate Southeast European environment and during the past decade, aimed at assessing their potential for yields of forage dry matter and aboveground biomass nitrogen and their economic reliability via land equivalent ratio. This review provides a cross-view of the most important deliverables of our applied research, including eight annual legume crops and six brassica species, demonstrating that nearly all the intercrops were economically reliable, as well as that those involving hairy vetch, Hungarian vetch, Narbonne vetch and pea on one side, and fodder kale and rapeseed on the other, were most productive in both manners. Feeling encouraged that this pioneering study may stimulate similar analyses in other environments and that intercropping annual legume and brassicas may play a large-scale role in diverse cropping systems, our team is heading a detailed examination of various extended research.

Soil and water conservation benefits of cover crops have been hypothesized as a way to mitigate and adapt to changing climatic conditions, but they can also have detrimental effects if rainfall is limited. Our objective was to quantify effects of winter cover crops on soil water storage and yield of silage maize under the agro-ecological conditions within Vojvodina Province in Serbia. The experiment was conducted under rain-fed conditions at three locations and included a control (bare fallow) plus three cover crop and two N rate treatments. The cover crop treatments were common vetch (Vicia sativa L.), triticale (x Triticosecale Wittm. ex A. Camus) and a mixture of the two species. All were managed as green manure and subsequently fertilized with either 120 or 160 kg N ha −1 before planting silage maize (Zea mays L.). Cover crop effects on soil water storage were calculated for two periods, March-May and May-September/October. A Standardized Precipitation Index (SPI) used to characterize drought severity for 2011/2012 and 2012/2013, showed values of 3 and 9, respectively, for the two periods. Soil water storage was reduced by all cover crop treatments, with the greatest deficiency occurring during the extremely dry year of 2012. Previous studies have shown cover crop growth reduced by soil water depletion during their growing season and negative effects on early-season growth and development of subsequent cash crops such as silage maize, but if rainfall is extremely low it can also reduce cash crop yield. This detrimental effect of cover crops on soil water balance was confirmed by correlations between soil water storage and maize silage yield.Atmosphere 2018, 9, 492 2 of 18 precipitation [8], which is more likely to be mitigated on fertile and well-structured soils. The level of soil organic matter, and therefore soil carbon content, positively influence the stability of soil aggregates and soil moisture retention under extreme precipitation or drought [9][10][11]. Several management practices can be the bond between the requirements to adapt to the weather changes and to stop the reduction or to increase soil fertility, such as by reducing or eliminating tillage, growing cover crops, and applying organic fertilisers.Because livestock production in Serbia and, therefore, the availability of organic fertilisers are low, research focuses on cover cropping. Additionally, reduced or no tillage is uncommon because of requirements for adequate machines, which significantly limit its application on small and medium farms. Cover crops have several uses, including preventing erosion, increasing organic matter content, improving nitrogen balance and soil properties, and suppressing weeds, among others [12,13]. Cover crops in crop rotations are not a common practice primarily because growing cover crops usually includes crops that do not result in economic return and often do not allow sufficient time for soil preparation for cash crops. Additionally, cover crops may reduce soil moisture for the subsequent crop in specifi...

In temperate regions, normal-leafed field pea still represents an important crop for grain and animal consumption, even though there is increasing interest in afila type cultivars because of their better standing ability. The effect of dual legume intercropping on grain yield of normal-leafed pea was studied during 2015 and 2016 in order to reduce lodging, to improve grain yield stability and to analyse the competitiveness of field pea with annual legumes and wheat. The research involved six species grown as sole crops: normal-leafed pea (Pisum sativum L. (Partim)), semi-leafless pea (Pisum sativum L. (Partim), faba bean (Vicia faba L. (Partim)), white lupin (Lupinus albus L.), fenugreek (Trigonella foenum-graecum L.) and wheat as a control (Triticum aestivum L. emend. Fiori et Paol) and intercrop mixtures of normal-leafed pea with other five species. Grain yield (t ha-1), yield components, land equivalent ratio, relative crowding coefficient and aggressivity value for grain yield were monitored. The highest grain yield of normal-leafed pea (2.87 t ha-1) was obtained from the mixture with semi-leafless pea in 2015 and from the mixture of wheat + normal-leafed pea (5.26 t ha-1) in 2016. The lowest number of pods and seeds per plant was formed by normal-leafed pea as a sole crop in 2015 (5.2 and 19.2, respectively). The obtained results showed that a thousand seed weight differed between treatments; however, the differences were not significant. The highest land equivalent ratio (1.40), relative crowding coefficient (4.44) and the positive value of aggressivity (0.19) were observed in the mixture of fenugreek + normal-leafed pea. The results demonstrated that semi-leafless + normalleafed pea and fenugreek + normal-leafed pea are the most beneficial mixtures for grain production, while faba bean was a less suitable component for intercropping with normal-leafed pea.