Short-term effects of defoliation on herbage productivity and herbage quality in a semi-arid grassland ecosystem of Inner Mongolia, P.R. China

The vast grassland steppes of Inner Mongolia have been heavily degraded due to overgrazing in the last decades, so that the consequences of grassland degradation are today the main ecological and socio-economical problems in the region. The major objective of the presented work was to describe short-term effects of defoliation using (i) plant related parameters and (ii) herbage quality parameters. A field experiment was carried out, simulating different levels of grazing stress by cutting. Additionally, a grazing experiment was established and the digestibility of herbage ingested and herbage on offer was compared between different grazing intensities to test for differences in selective feed intake. The field experiment was carried out in 2004 and 2005. A natural grassland sward was exposed to three different cutting frequencies. The biomass yield, as well as nitrogen uptake, and with it the crude protein content, were significantly increased due to higher cutting frequency. Short-term differences in root mass and root carbohydrate reserves, as well as differences in species composition and tiller density were not significant. The herbage quality parameters cell wall content and -composition, the organic matter digestibility (OMD) and the non-structural carbohydrate content showed significant changes, but these were not consistent, neither between treatments nor between years. The herbage quality parameters were more influenced by climatic and seasonal fluctuations, than by the tested cutting frequencies. The increase in biomass yield and crude protein content in frequently cut treatments demonstrated, that the grassland steppe was resistant in the short-term to high defoliation intensity even in extremely dry years like 2005. The grazing experiment started in 2005 and the data obtained in this year were analysed to answer the question, if OMD of ingested herbage was underestimated by in vitro determined OMD of herbage on offer, what can be expected due to selective feed intake of grazing animals. When herbage on offer decreases, one would expect that OMD of herbage offered and OMD of herbage ingested converge, as grazing animals have less opportunity to select. As expected, herbage on offer significantly decreased with increasing grazing intensity. However, OMD was not significantly different between grazing intensities, the expected effects of selective grazing were not assessed. The observation that the animals did not graze selectively, or were not able to, was supported by two other observations: firstly, the vertical quality structure of herbage on offer was very homogenous in 2005 and secondly, the necrotic material proportion of herbage offered was relatively constant across all grazing intensities. High defoliation intensities have positive effects on productivity and to some extent on herbage quality of the grassland vegetation in the short-term. Nevertheless it became clear, that climatic fluctuations, especially the amount of precipitation, have a fundamental influence on the grassland ecosystem.Durch Überbeweidung wurden die Grasland-Steppen der Inneren Mongolei in den letzten Jahrzehn-ten stark degradiert, so dass dies heute das vordringlichste ökologische und sozio-ökonomische Problem in dieser Region ist. Das Ziel der vorliegenden Arbeit war es, kurzfristige Effekte von Be-weidungsstress durch (i) pflanzenbaulich relevante Parameter, sowie (ii) Futterqualitätsparameter zu beschreiben. Diese Untersuchungen wurden in einem Feldexperiment durchgeführt, in dem Bewei-dungsstress durch verschiedene Schnittintensitäten simuliert wurde. Des Weiteren wurde in einem Beweidungsexperiment die Verdaulichkeit des aufgenommen und des angebotenen Futters in ver-schiedenen Beweidungsintensitäten verglichen, um erwartete Unterschiede im Hinblick auf selekti-ve Futteraufnahme zu überprüfen. Das Feldexperiment wurde in den Jahren 2004 und 2005 durchgeführt, dabei wurde ein natürlicher Graslandbestand drei verschiedenen Schnittintensitäten ausgesetzt. Die Biomasseproduktion, sowie die Stickstoffaufnahme, und damit der Rohproteingehalt, wurden durch höhere Schnittintensitäten signifikant gesteigert. Kurzfristige Veränderungen der Wurzelmasse und der Kohlenhydratreserven in der Wurzel wurden, ebenso wie Veränderungen der Artzusammensetzung und der Triebdichte, nicht beobachtet. Die Futterqualitätsparameter Zellwandgehalt und -zusammensetzung, sowie die Verdaulichkeit der Organischen Masse (OMD) und die Gehalte an Nicht-Strukturkohlenhydraten, zeigten zum Teil signifikante Veränderungen. Diese waren allerdings weder zwischen den Behand-lungen, noch zwischen den Jahren konstant. Die Futterqualitätsparameter wurden stärker durch wit-terungsbedingte Schwankungen und Saisoneinflüsse beeinflusst, als durch die geprüften Schnittin-tensitäten. Der Anstieg des Biomasseertrags und des Rohproteingehalts durch intensivere Schnitt-nutzung zeigte, dass die Grasland-Steppe kurzfristig einer intensiven Nutzung widerstehen kann, sogar unter Trockenstressbedingungen wie im Jahr 2005. Das Beweidungsexperiment startete im Juni 2005. Anhand einjähriger Daten wurde geprüft, ob die OMD des tatsächlich aufgenommenen Futters durch die in-vitro ermittelte OMD des angebotenen Futters unterschätzt wird, was durch Selektion der Weidetiere zu erklären wäre. Wenn das Futter-angebot sinkt, dann sollte die OMD des angebotenen Futters der OMD des aufgenommenen Futters entsprechen, da den Weidetieren kaum Möglichkeit zur Selektion bleibt. Das Futterangebot war wie erwartet in den hohen Beweidungsintensitäten signifikant geringer. Die OMD war aber zwischen den Beweidungsintensitäten nicht signifikant verschieden, so dass die erwarteten Selektionseffekte aus blieben. Zwei weitere Beobachtungen stützen die Aussage, dass die Weidetiere im Jahr 2005 kaum selektiert haben, bzw. selektieren konnten: erstens, die Qualitätsstruktur des angebotenen Fut-ters war in sich sehr homogen und zweitens, war der Anteil an nekrotischer Biomasse im angebote-nen Futter über alle Beweidungsintensitäten relativ konstant. Höhere Nutzungsintensitäten haben kurzfristig einen positiven Effekt auf die Produktivität, und z.T. auf die Futterqualität der Graslandvegetation. Es wurde deutlich, dass witterungsbedingte Schwan-kungen, insbesondere des Niederschlags, einen fundamentalen Einfluss auf das Grasland-Ökosystem haben

Effects of charcoal-enriched goat manure on soil fertility parameters and growth of pearl millet (Pennisetum glaucum L.) in a sandy soil from northern Oman

The effect of charcoal feeding on manure quality and its subsequent application to enhance soil productivity has received little attention. The objectives of the present study therefore were to investigate the effects of (i) charcoal feeding on manure composition, and (ii) charcoal-enriched manure application on soil fertility parameters and growth of millet (Pennisetum glaucum L.). To this end, two experiments were conducted: First, a goat feeding trial where goats were fed increasing levels of activated charcoal (AC; 0, 3, 5, 7, and 9% of total ration); second, a greenhouse pot experiment using the manure from the feeding trial as an amendment for a sandy soil from northern Oman. We measured manure C, N, P, and K concentrations, soil fertility parameters and microbial biomass indices, as well as plant yield and nutrient concentrations. Manure C concentration increased significantly (P0.001) from 45.2% (0% AC) to 60.2% (9% AC) with increasing dietary AC, whereas manure N, P, and K concentrations decreased (P0.001) from 0% AC (N: 2.5%, P: 1.5%, K: 0.8%) to 9% AC (N: 1.7%, P: 0.8%, K: 0.4%). Soil organic carbon, pH, and microbial biomass N showed a response to AC-enriched manure. Yield of millet decreased slightly with AC enrichment, whereas K uptake was improved with increasing AC. We conclude that AC effects on manure quality and soil productivity depend on dosage of manure and AC, properties of AC, trial duration, and soil type

Swamp buffalo keeping – an out-dated farming activity? A case study in smallholder farming systems in Xishuangbanna, Yunnan Province, PR China

Expansion of rubber tree plantations and agricultural mechanization caused a decline of swamp buffalo numbers in the Naban River National Nature Reserve (NRNNR), Yunnan Province, China. We analysed current use of buffaloes for field work and the recent development of the regional buffalo population, based on interviews with 184 farmers in 2007/2008 and discussions with 62 buffalo keepers in 2009. Three types of NRNNR farms were distinguished, differing mainly in altitude, area under rubber, and involvement in livestock husbandry. While pig based farms (PB; n=37) have abandoned buffalo keeping, 11% of the rubber based farms (RB; n=71) and 100% of the livestock-corn based farms (LB; n=76) kept buffaloes in 2008. Herd size was 2.5 +/-1.80 (n=84) buffaloes in early 2008 and 2.2 +/-1.69 (n=62) in 2009. Field work on own land was the main reason for keeping buffaloes (87.3 %), but lending work buffaloes to neighbours (79.0%) was also important. Other purposes were transport of goods (16.1%), buffalo trade (11.3%) and meat consumption (6.4%). Buffalo care required 6.2 +/-3.00 working hours daily, while annual working time of a buffalo was 294 +/-216.6 hours. The area ploughed with buffaloes remained constant during the past 10 years despite an expansion of land cropped per farm. Although further replacement of buffaloes by tractors occurs rapidly, buffaloes still provide cheap work force and buffer risks on poor NRNNR farms. Appropriate advice is needed for improved breeding management to increase the efficiency of buffalo husbandry and provide better opportunities for buffalo meat sale in the region

Einfluss des Kraftfutterniveaus in der ökologischen Milchviehhaltung

A feeding trail was carried out in the Organic Dairy Farm of “Haus Riswick“, Kleve, Germany between 1st August 2002 and 31st October 2003 in order to a) investigate the frequently asked question after the “optimal” concentrate-level in Organic Farming and b) relate the concentrate amount to potential health problems of herds associated to the change into Organic Farming. The herd was split into 2 groups of 18 cows. A high quality forage ration was fed to both groups which allowed maintenance plus 19 kg of ECM production on average, which was composed of grass and maize silage in winter, and additional pasture in summer time. The Control-Group (C) received concentrates according to their milk yield, but was not given more than 8 kg/d. The Experimental-Group (E) was fed 3 kg extra concentrates mixed with the forage ration, but did not receive more than 11 kg/d of concentrates in total. Therefore differences between the groups occurred in the first weeks of lactation and in the end of lactation. In 305-day-lactation the C-Group consumed 1600 kg concentrates and the E-Group consumed 2200 kg per cow per year. The results showed a large difference between the seasons. During summer, when cows had access to pasture (half-day), the milk yield was not different between the groups, although the E-Group consumed on average 1,5 kg DM concentrates more than the C-Group. In winter the E-Group produced about 4 kg ECM more than the C-Group. During winter the E-Group consumed 2 kg DM/d concentrates more, which was utilized for milk production. Protein-content in milk showed no differences, fat-content was slightly higher for the C-Group throughout the trial. The results also showed that especially in the first 100 days of lactation the differences between the groups were the largest. The BCS was sufficient during the first 200 days of lactation, even though it was below the optimal score. After 200 days the BCS dropped under the sufficient level, but when cows calved again the BCS was on a sufficient status again. That means that in the last weeks of lactation and in the dry-off period the cows again gained condition

Varying the dietary supply of C and N to manipulate the manure composition of water buffalo heifers in Oman

Optimizing the composition of manure has the potential to reduce nutrient losses to the environment and to increase crop yields. In this study the effect of dietary ratios of carbon (C) to nitrogen (N) and neutral detergent fibre (NDF) to soluble carbohydrates (SC) on faeces composition of water buffalo heifers was assessed. Two digestibility trials were conducted with 12 animals each, fed one control and four test diets composed to achieve (1) high C/N and high NDF/SC ratios (HH), (2) low C/N and low NDF/SC ratios (LL), (3) high C/N and low NDF/SC ratios (HL) and (4) low C/N and high NDF/SC (LH) ratios. Faecal C/N ratios were generally lower than dietary C/N ratios, but the reduction was especially large for high C/N ratio diets (HH=55 %, HL=51 %). Faecal N concentration was positively correlated (r^2 = 0.6; P < 0.001) with N intake, but the increase in faecal N was more pronounced for diets that supplied low amounts of N. Faecal NDF concentration was positively related to NDF intake (r^2 = 0.42; P < 0.001), as well as the faecal C/N ratio (r^2 = 0.3; P < 0.001). Results demonstrate that C/N ratio and NDF concentration of buffalo manure were affected by diet composition. Diets with high C/N ratio and low NDF/SC ratio are preferable with regard to manure quality, but may not satisfy the nutritional requirements of producing animals, since N concentration in these diets was low and fibre concentration simultaneously high

Selective grazing and seasonal precipitation play key roles in shaping plant community structure of semi-arid grasslands

Many studies have examined how intensity of grazing and patterns of precipitation individually and interactively influence the spatial and temporal dynamics of grassland vegetation, such as dominance, succession, coexistence, and spatial heterogeneity. However existing models have rarely considered the diet preferences of grazers and how they interact with variation in precipitation amount and timing. We examined how plant community structure responds to the individual and combined effects of grazing intensity, selective grazing, and patterns of precipitation, based on a six-year grazing experiment with seven levels of field-manipulated grazing intensity in a typical steppe of Inner Mongolia. The palatable species, mainly forbs, were most severely damaged at intermediate levels of grazing intensity; given that these species are the major contributors to plant community diversity, a U-shaped diversity-grazing intensity relationship resulted. In contrast, spatial heterogeneity of aboveground biomass and species composition peaked at intermediate levels of grazing intensity. Cold season precipitation positively correlated with the abundance of the dominant C-3 grasses and correlated negatively with the subdominant forbs and C-4 plants. Thus, when cold season precipitation increased, plant community species diversity decreased. Grazing intensity and precipitation did not interact in their effects on species richness. These findings contrast with the predictions from current disturbance-diversity models and indicate that diet selection of grazing animals is an important factor shaping the diversity-grazing intensity relationship in semi-arid grasslands. Future grassland biodiversity conservation and management practices should take diet preference of grazing animals into account