Carbon and nutrient stocks of tea plantations differing in age, genotype and plant population density

Tea (Camellia sinensis L.) is a perennial evergreen shrub managed intensively for continuous growth of young shoots. Most tea plantations were established at the expense of native forest. Change in carbon (C) and nutrient (nitrogen, phosphorus, potassium (NPK)) accumulation in forests over time has been intensively studied, but how C and NPK stocks in tea plantations are associated with age, genotype and plant density have not been reported yet in literature. To get a better insight in the effects of age and the associated change in genotype (clone or seedling) and density on C and NPK stocks data were collected in a chronosequence of tea plantations by destructive sampling of whole tea bushes. Four plantations differing in age (76-, 43-, 29- and 14-year old) and genotype¿density combinations were selected. The 76- and 43-year old plantations were composed of seedlings planted at a relative low density: a spacing of 1.52¿×¿0.91 m and 1.22¿×¿1.22 m, respectively, whereas in the 29- and 14-year old plantations an improved clonal cultivar was grown at higher plant densities: a spacing of 1.22¿×¿0.61 m and 1.22¿×¿0.76 m, respectively. Total dry matter weights (DM) of tea bushes increased with age from 9.0 to 11.5 kg in clonal bushes and from 13.5 and 19.9 kg in seedling bushes for the 14- and 29-year, and the 43- and 76-year old plantations, respectively. Most DM was stored in the woody tissue of the tea bush frame. Total C- stocks expressed per unit area (ha) amounted to 44 and 72, and 43 and 69 t C ha¿1 for clonal and seedling bushes, respectively. Total N stocks ranged from 732 to 995 and from 734 to 1,200 kg ha¿1, P stocks from 78 to 120 and from 67 to 92 kg ha¿1, and K stocks from 775 to 901 and from 646 to 1,120 kg ha¿1 for clonal and seedling bushes, respectively. It is concluded that older stands of seedling and clonal tea plantations result in higher C and NPK stocks. Higher stocks may be functional in maintaining yield stability under adverse weather conditions. Plantations with higher nutrient stocks are less responsive to nutrient supply and therefore will require lower fertilizer applications

'Houd meerdere opties open'

Boeren staan voor de vraag of ze moeten investeren in mestverwerking of niet. Maar de vraag is ook of de samenleving een hightech intensieve veehouderij met mestverwerking accepteert. Je loopt de kans dat als je een deel van het vraagstuk oplost, je de oplossingen van andere aspecten juist moeilijker maak

Regionaal nutriëntenmanagement; een verkenning van perspectieven en beperkingen

De van oudsher monofunctionele landbouw verandert steeds meer in een multifunctionele landbouw, waarin meerdere functies van het landelijke gebied worden verweven. Met behulp van regionaal nutriëntenbeheer kan worden ingespeeld op regiospecifieke landbouwkundige, milieukundige en economische randvoorwaarden die aan landbouw worden gesteld. In deze studie zijn perspectieven en beperkingen van regionaal nutriëntenbeheer verkend. Voor veel landbouwbedrijven is een forse inspanning nodig om aan de normenvan het voorgenomen uniforme mestbeleid te voldoen. In sommige regio's zijn wellicht stringentere normen nodig en in andere regio's wellicht minder stringente. Regionaal nutriëntenbeheer speelt hierop in. Perspectieven voor regionaal nutriëntenbeheer liggen vooral in het beheer van nutriëntenstromen tussen verschillende (landbouw)sectoren in een regio, de aanpak van specifieke milieuproblemen, regionale bemestingsadviezen, landbouwvoorlichting en waterbeheer

Effects of ageing and cultivation of grassland on soil nitrogen

Nitrogen losses from agriculture in the Netherlands have to be strongly decreased because of national and international policy (e.g. Nitrate Directive). The cultivation of grassland when grassland is renewed or converted into arable land may enhance net nitrogen mineralization and, thereby, nitrogen losses via leaching and denitrification. These nitrogen losses can be decreased by adjustment of management, but a good insight into the soil processes during ageing and after cultivation of grassland is required. A literature study was carried out to quantify the effects of ageing and cultivation of grassland on nitrogen losses from the soil. The study shows that the risk on losses increases when grassland age increases, the period between cultivation and reseeding increases and the nitrogen uptake capacity of the next crop decreases. In the Netherlands, only a few studies have been carried out and, especially, a quantification of the effects of cultivation on nitrogen losses under Dutch conditions is lacking. It is recommended to set up integral field studies in which both the agricultural and environmental effects of grassland cultivation are quantified. The results must be used to develop measures and tools to achieve environmentally and agriculturally sound systems of permanent and temporal grasslands

Dryland maize yields and water use efficiency in response to tillage and nutrient management practices in China

Rainfed crop production in northern China is constrained by low and variable rainfall. This study explored the effects of tillage and nutrient management practices on maize (Zea mays L.) yield and water use efficiency (WUE), at Shouyang Dryland Farming Experimental Station in northern China during 2003-2008. The experiment was set-up using a split-plot design with 3 tillage methods as main treatments: conventional, reduced (till with crop residue incoperated in fall but no-till in spring), and no-till. Sub-treatments were 3 NP fertilizer rates: 105-46, 179-78 and 210-92 kg N and P ha. -1 Maize grain yields were greatly influenced by the amount of growing season rainfall, and by soil water contents at sowing. Mean grain yields over the 6-year period in response to tillage treatments were 5604, 5347 and 5185 kg ha, under reduced, no-till and conventional tillage, respectively. Mean WUE was 13.7, 13.6 and 12.6 kg ha mm under reduced, no-till, and conventional tillage, respectively. Mean soil water contents at sowing and at harvest were significantly influenced by tillage treatments. At harvest time, the no-till treatment had ~8-12% more water in the soil than the conventional and reduced tillage treatments. Under conventional tillage, grain yields increased with NP fertilizer application rates. However, under reduced tillage, grain yields were highest with lowest NP fertilizer application rate. In conclusion, grain yields and WUE were highest under reduced tillage at modest NP fertilizer application rates of 105 kg N and 46 kg P per ha. No-till increased soil water storage by 8-12% and improved WUE compared to conventional tillage

Method and timing of grassland renovation affects herbage yield, nitrate leaching, and nitrous oxide emission in intensively managed grasslands

Managed grasslands are occasionally ploughed up and reseeded in order to maintain or increase the sward productivity. It has been reported that this renovation of grassland is associated with a flush of soil organic nitrogen (N) mineralization and with a temporary increase in soil mineral N contents. Here, we report on the effects of method and time of grassland renovation on herbage yield, nitrate (NO3 -) leaching and nitrous oxide (N2O) emission. Field experiments were carried out at three sites (two sandy soils and a clay soil) in the Netherlands for three years. Renovation of grassland increased the percentage of Perennial ryegrass from 48–70% up to more than 90%. However, averaged over three years, dry matter yields were higher for the reference (not reseeded) swards (on average 13.6 Mg ha-1 for the highest N application rate) than for the renovated grasslands (12.2–13.1 Mg ha-1 dry matter). Grassland renovation in April did not increase N leaching in comparison to the reference. However, renovation in September increased the risk of leaching, because mineral N contents in the 0–90 cm were in November on average 46–77 kg N ha-1 higher than in the reference. Contents of dissolved organic N (DON) in the soil were not affected by renovation. Renovation increased N2O emissions by a factor of 1.8–3.0 relative to the reference grassland. Emissions of N2O were on average higher after renovation in April (8.2 kg N2O-N ha-1) than in September (5.8 kg N2O-N ha-1). Renovation without ploughing (i.e. only chemically destruction of the sward) resulted in a lower percentage of perennial ryegrass (60–84%) than with ploughing (>90%). Moreover, N2O emissions were higher after renovation without ploughing than with ploughing. Clearly, farmers need better recommendations and tools for determining when grassland renovation has beneficial agronomic effects. Losses of N via leaching and N2O emission after renovation can probably not be avoided, but renovation in spring in stead of autumn in combination with ploughing and proper timing of fertilizer application can minimize N losses

Bodem en voedsel: wat dragen bodemkundigen bij?

Bodemkunde als wetenschap bestaat ongeveer 150 jaar. In dit artikel wordt geprobeerd de vraag te beantwoorden welke bijdragen bodemkundigen hebben geleverd aan de voedselvoorziening wereldwijd. Die vraag blijkt niet gemakkelijk te beantwoorden. Identificatie en waardering van landbouwgronden is een goede eerste; het identificeren en verbeteren van zure gronden is een vijfde thema. Een rondgang langs wetenschap en wetenschapper

Changing rural areas: exploring future agriculture in the Netherlands and EU

This booklet provides a brief overview of the results of 9 studies exploring the challenges, barriers and dilemmas of agriculture and rural areas in the next three decades. The purpose of these studies was to assist policy makers in (re)shaping policies for agriculture, environment and spatial planning. Each chapter quickly summarizes the major findings of a study and the lessons to be learned from that study. All studies have been carried out by researchers from Wageningen-UR and approaches, views and conclusions expressed may be biased to some extend by experiences from The Netherlands, where the 'transition towards sustainable agriculture' receives considerable attention from policy makers. Most studies presented here used the triple P concept (People, Planet, Profit) and a 'Roadmap' with five basic questions (Why? What? How? Where? How much?) as common framework for the analyse

How to manage changes in rural areas in desired direction?

Inventory of ideas (mind maps) of: Vaclav Smil (Manitoba), Krijn Poppe (LEI), Jan van Tatenhove (Amsterdam), Ina Horlings (Telos), Madeleine van Mansfeld (Alterra

Efficiency, economics, and environmental implications of phosphorus resource use and the fertilizer industry in China

Phosphorus (P) is an essential nutrient for crop production and is often in short supply. The necessary P fertilizers are derived from deposits in the lithosphere, which are limited in size and nonrenewable. China is one of the world's largest consumers and producers of P fertilizers. Thus, P resource use efficiency in China has an important impact on the worldwide efficiency of P resource use. This study examined the P fertilizer industry in China in terms of P resource use efficiency, economics, and environmental risk, and explored options for improvement through scenario analysis. P resource use efficiency decreased from a mean of 71% before 1995 to 39% in 2003, i.e., from every 10 kg P in rock material, only 3.9 kg P was used to produce fertilizer, 5.6 kg of the residues were discarded at the mining site, and 0.5 kg was manufacturing waste. The decreased efficiency was caused by increased P rock mining activities, especially from small, inefficient miners. Enhanced mining was supported by local governments and by the growing P fertilizer industry, where high-analysis P fertilizers have fourfold higher gross margins than traditional low-analysis fertilizers. Although the growing fertilizer industry is contributing significantly to the development of some regions, the economic efficiency is still lower than in other countries, e.g., in the USA. The P resource is depleting quickly, and the environmental consequences of inefficient use are serious. The amount of accumulated phosphor gypsum was estimated to be 110 Tg, the amount of deteriorated land reached 475 km(2), and the consumption of ground water was 1.8 billion m(3) per year. The low efficiency and serious environmental risk could be attributed to the numerous small inefficient miners, which were supported by intervention of governmental subsidies and taxes after 1995. This study proved that there is a great deal of room for improvement in the resource use efficiency up to 77% by integrated measures, which need broad cooperation of miners, fertilizer plants, and agriculture