Pasture Growth Research Articles

Can Lotus pedunculatus over-sowing in low-fertility tussock country increase farm resilience?

The range of legumes to boost farm productivity in low-fertility hill country are limited. Lotus pedunculatus (Lotus) provides an option when soil pH is below 5 but is intolerant to severe and regular grazing. However, itcan be used at sites that are only grazed occasionally during spring summer and autumn. Oversowing of Lotus pedunculatus has been used to improve 17% of the total area of Avenel Station, Millers Flat. Measurements of pasture growth and animal production were collected over three years post-sowing, indicating a doubling of pasture production from the native form while providing liveweight gains of 0.135 and 0.75 kg/d in lambs and yearling cattle respectively. Systems modelling was used to re-examine the current farm-system configuration to test the possible outcomes from implementing further enterprises that may capture the increased late spring and summer production effectively. Reducing ewe numbers and concentrating on improving lamb survival were the most cost-effective and environmentally effective options. Buying in further finishing lambs to use the summer surplus also improved profitability. Increasing cow numbers was similarly profitable. Increasing ewe numbers also required an increase in winter feed supply and was the least profitable way to capture the benefits. Testing using climatic extreme scenarios demonstrated that the oversowing of Lotus on the higher, wetter tussock country increased the resilience of the farm by providing a buffer during dry summers.

Mitigation of saturation in satellite pasture measurement via incorporation of a statistical pasture growth model

Measurement of pasture biomass is useful to farmers, as it enables timely and accurate management decisions. Satellite pasture measurement allows this information to be obtained with minimal time and labour on the part of the farmer. However, the accuracy of satellite measurements for high levels of pasture biomass can be impacted by a phenomenon called saturation, in which the response of the satellite estimate to increased biomass is diminished in situations of high biomass. In this investigation, a statistical pasture growth model was combined with satellite pasture measurements, with the aim of mitigating the effect of saturation on estimation accuracy. Data were captured for five farms, across two regions and an 18–21 month measurement period. Where satellite measurements appeared to be saturated, the growth model estimate was substituted. This process resulted in improved accuracy (R2 improved from 0.672 to 0.703; RMSE improved from 334 to 309 kg DM/ha; and average bias improved from -62 to -9 kg DM/ha). The statistical improvements were more pronounced where terrestrial estimates were higher so the impact of saturation would be greatest. These results indicate that the problem of saturation in satellite pasture measurement can be addressed by the incorporation of modelled data.
 Prior research has predicted that improved accuracy of pasture measurement would be associated with increased profitability, and this work helps achieve that goal for farmers using satellite measurement services.

Quantifying the value proposition for white clover persistence on a New Zealand summer-dry hill-country farm

The improvement in forage quality and quantity of summer-dry hill country pasture resulting from the introduction of clover is well recognised. However, ensuring the persistence of the commonly availablecultivars is challenging, in the face of seasonal moisture stress, intensive grazing, competition from established well-adapted pasture species, low soil fertility and low soil pH – conditions typical of the East Coast of the North Island. Here we quantify the value proposition associated with the introduction of white clover into a case study on a Gisborne sheep and beef farm, using a six-step process. A topographically explicit approach is taken, using an understanding of the underlying spatial variability, based on a combination of soil and pasture measurements, APSIM simulation modelling of pasture growth and farm system modelling of enterprise performance. We show that from a baseline of a typical low-fertility, diverse species hill country pasture, white clover introduction can increase spring and summer forage consumption by 17%, enabling inclusion of an additional 6-month bull finishing enterprise generating a 32% greater carcass weight production and leading to a 49% improvement in farm system EBIT. This represents a positive net present value of over $360,000 for the original investment in white clover establishment into existing pastures.

Understanding water losses from irrigated pastures on loess-derived hillslopes

Irrigation is likely to increase water losses from hillslopes, particularly on loess-derived soils with impeded drainage. This is important as irrigation of these soils in New Zealand is increasing. A field site was established to measure runoff from a pasture hillslope irrigated by a centre-pivot in South Canterbury. Between November and March, 161 and 199 mm of irrigation was applied, with 23% more at the bottom of the slope. Runoff varied with position in the hillslope, with 3.5 times from the bottom plot (52 mm) compared to the top. Over the length of the slope (40 m) this represents a potential loss of 9% of precipitation, or 21% of the irrigation. Evidence for saturation excess and infiltration excess runoff was observed, with antecedent soil moisture conditions being a key factor. Pasture production and water use efficiency (WUE) also varied with slope, the least (4.6 t DM/ha or 12 kg DM/ha/mm) observed at middle and most at the top of the slope (10.1 t DM/ha or 23 kg DM/ha/mm). This was likely due to a combination of differences in radiation and soil conditions. There was indication that pasture growth was limited by water availability at the top and potentially excess at the bottom of the slope. Our results indicate potential for improving irrigation practices.

Impact of winter fodder beet or kale allocation on body condition score gain and early lactation performance of dairy cows

Forage crops such as fodder beet (FB) and kale are an important feature of dairy farming in Southland and Otago where winter pasture growth is negligible. However, farmers are concerned about poor performance of cows following winter FB feeding. In winter 2017, cows were offered FB or kale both with pasture baleage at two allocation rates: target (crop allocated to achieve a winter body condition score (BCS) gain of 0.7) or high (ad libitum crop). Diets with FB were lower in fibre, phosphorus, sulphur and calcium, but had a higher metabolizable energy, compared with kale diets. Body condition change and early lactation performance were monitored to compare effects of winter FB and kale diets. Average daily BCS gain before calving was similar for FB and kale cows. Crop type had a greater impact on cow performance than allocation rate. Cows wintered on FB had better reproductive performance (3-week pregnancy rate), and greater average milk solids, fat and protein yield (kg/d) than cows wintered on kale. Therefore, winter FB did not reduce cow performance compared with kale. However, the cumulative effects of a FB diet long term are yet to be determined and future research should monitor the impact on animal health.

The effect of polyferric sulphate treated farm dairy effluent and clarified water on leaching losses, greenhouse gas emissions and pasture growth

ABSTRACT A lysimeter experiment was conducted to investigate the environmental effects of applying farm dairy effluent (FDE) treated with a chemical coagulant (polyferric sulphate) to land. The coagulant was administered as part of an effluent treatment system known as ClearTech. Two products are produced from the treatment process; treated effluent (TE) and clarified water (CW). Applications were applied in May. When compared to FDE, TE and CW reduced E. coli, Total-P and dissolved reactive P (DRP) leaching losses. Escherichia coli leaching losses were reduced by 99.97% and 99.99% for TE and CW, respectively. This was because of the acidity of the added coagulant and the encapsulation of the bacteria in the flocculated sediment. Compared to FDE, Total-P leaching losses were reduced by 90.5% and 85.7% for TE and CW, respectively. DRP leaching losses were also reduced under TE and CW by 99.5% and >99.99%, respectively. Reductions in phosphorus leaching were attributed to the reduced P solubility, resulting from the iron added in the coagulant binding to the phosphorus. There was no significant difference between treatments in the amount of iron leached, greenhouse gas emissions or Mineral-N leached (except where additional ammonium-N was added to the clarified water).

Can Nitrogen Source and Nitrification Inhibitors Affect In-Season Nitrogen Supply?

ABSTRACT This study sought to identify whether piggery effluent-derived nitrogen sources can be formulated with urea and nitrification inhibitors to better synchronize nitrogen (N) supply with crop demand than conventional urea fertilizer alone. A 288 pot pasture growth and leaching growth accelerator trial (5 pasture cuts) was completed with a factorial treatment structure of three N sources (2.63 g N [kg soil]−1 applied as 100% urea-N, 8% struvite-N + 92% urea-N, and 8% piggery pond sludge-N + 92% urea-N), five rates of three nitrification inhibitors (including 3,4-Dimethylpyrazole phosphate, DMPP; limonene+ethanol; and dicyandiamide, DCD), and matrix encapsulated forms of these inhibitors. Applying a combination of piggery sludge with urea increased N uptake during the first 4 weeks of plant growth (by 65%), though total N uptake throughout the trial (22 weeks) did not differ across the N-sources. The microbial community of the soil to which the sludge was added was significantly different from the un-amended soil at the conclusion of the trial. All inhibitor formulations significantly decreased leaching losses of mineral-N relative to the control (by 14 to 61%). The use of DMPP decreased initial nutrient uptake, deferring uptake until later in the experiment. Inhibitor addition resulted in microbial community effects that persisted throughout the trial. The study demonstrated that a piggery-derived N-source and a nitrification inhibitor can be used to manipulate plant N uptake to occur later or earlier in a growing period with equal cumulative uptake, achieving an 11% increase in residual N store, and decreased N leaching losses.

Enhancing bird-mediated seed dispersal to increase rainforest regeneration in disused pasture – A restoration experiment

Frugivorous birds are important seed dispersers but are infrequent visitors to pasture. Therefore, the recruitment of rainforest trees into disused pasture is often limited by dispersal. We studied potential seed sources, seed-dispersing birds, seed rain and seedling recruitment in an experimental management project that aimed to catalyse rainforest regeneration adjacent to old-growth forest in north-eastern Australia. To attract birds, nine semi-natural perches and water basins were installed in each of three 0.64 ha experimental plots, concurrent with herbicide control of pasture grasses. Despite a diverse avian seed-disperser community in the adjacent forest, only three species visited the plots. However, the presence of water increased seed deposition. Water basins collected twelve times as many native tree seeds as mesh seed traps (a 24-fold increase in seed deposition per unit area), including more large seeds (≥10 mm), and more species, especially of bird-dispersed forest trees. This was due to the large-gaped Pied Currawong (Strepera graculina) that deposited large seeds beneath the perches, when using water to regurgitate seeds. Deposition of large native forest tree seeds was also enhanced under perches positioned close to an already established tree or large shrub, highlighting an important indirect effect of pasture trees. Such pasture trees can themselves be effective regeneration nuclei, and their function improved by actions to suppress pasture growth and encourage dispersers. However, in this study, these interventions were not sufficient to fully mitigate barriers to rainforest regeneration. Although seed deposition was enhanced by the presence of water, semi-natural perches and pasture trees, recruited seedlings in the plots were not representative of the seed deposited. Instead they were dominated by a subset of small-diaspore, pioneer species. To further test the potential for semi-natural perches, water and pasture suppression to increase rainforest regeneration in disused pasture, requires testing of water source designs and carefully designed experimental restoration to examine dispersal and other regeneration barriers.

Grazing under Irrigation Affects N2O-Emissions Substantially in South Africa

Fertilized agricultural soils serve as a primary source of anthropogenic N2O emissions. In South Africa, there is a paucity of data on N2O emissions from fertilized, irrigated dairy-pasture systems and emission factors (EF) associated with the amount of N applied. A first study aiming to quantify direct N2O emissions and associated EFs of intensive pasture-based dairy systems in sub-Sahara Africa was conducted in South Africa. Field trials were conducted to evaluate fertilizer rates (0, 220, 440, 660, and 880 kg N ha−1 year−1) on N2O emissions from irrigated kikuyu–perennial ryegrass (Pennisetum clandestinum–Lolium perenne) pastures. The static chamber method was used to collect weekly N2O samples for one year. The highest daily N2O fluxes occurred in spring (0.99 kg ha−1 day−1) and summer (1.52 kg ha−1 day−1). Accumulated N2O emissions ranged between 2.45 and 15.5 kg N2O-N ha−1 year−1 and EFs for mineral fertilizers applied had an average of 0.9%. Nitrogen in yielded herbage varied between 582 and 900 kg N ha−1. There was no positive effect on growth of pasture herbage from adding N at high rates. The relationship between N balance and annual N2O emissions was exponential, which indicated that excessive fertilization of N will add directly to N2O emissions from the pastures. Results from this study could update South Africa’s greenhouse gas inventory more accurately to facilitate Tier 3 estimates.

APSIM-Tropical Pasture: A model for simulating perennial tropical grass growth and its parameterisation for palisade grass (Brachiaria brizantha)

Tropical grasses are used as forage, to produce energy from biomass, for land restoration and carbon sequestration, among other applications. Many modelling approaches have been employed to simulate tropical grasses growth, but these have several limitations that must be solved by adapting them or creating new models. This study aimed to develop a tropical pasture model in the Agricultural Production Systems Simulator (APSIM) modelling framework, and to parameterise it to simulate Brachiaria brizantha ‘BRS Piatã’ growth, under grazing and cut-and-carry management. For this, three field experiments were conducted in the South-east of Brazil where pasture growth was measured in a cut-and-carry system, with irrigated and rainfed treatments, and in a rainfed grazing system. Model evaluation was performed through precision and accuracy indices and simulation errors. Under cut-and-carry management, forage productivity was estimated with R2 values from 0.89 to 0.94, Willmott agreement indices between 0.97 and 0.98, and Nash-Sutcliffe Efficiency values of 0.88 to up to 0.92. This demonstrates the capacity of the APSIM-Tropical Pasture model to simulate tropical pastures. Simulation of phenology, early growth after sowing, partitioning and senescence during flowering, and reallocation and retranslocation of plant dry matter and nitrogen were important aspects for this capacity. Then, APSIM-Tropical Pasture can be used to simulate tropical pastures, but several requirements for further improvements have been identified, such as to improve the simulations of flowering for palisade grass, N effects on pasture yield, reallocation and retranslocation processes. Under grazing management, forage productivity was estimated with R2 = 0.80, Willmott agreement index of 0.91, and Nash-Sutcliffe Efficiency value of 0.62. Despite these reasonable results, simulations presented problems, since does not take into account the effect of grazing animals on pastures. This indicates that, in its current form, APSIM-Tropical Pasture is not able to simulate pastures under grazing effectively. However, this simulation of grazed system was important to identify main modelling constraints and direct future research to improve knowledge of processes and interactions needed for pasture model development.

Growth and nutrient uptake of temperate perennial pastures are influenced by grass species and fertilisation with a microbial consortium inoculant

AbstractBackground: The low fertility of sandy soils in South‐Western Australia is challenging for the establishment of temperate perennial pastures.Aims: To assess whether microbial consortium inoculant may improve plant growth by increasing nutrient supply, root biomass and nutrient uptake capacity.Methods: Five temperate perennial pasture grasses–cocksfoot (Dactylis glomerata L. cv. Howlong), phalaris (Phalaris aquatica L. cv. Atlas PG), tall fescue (Festuca arundinacea L. cv. Prosper), tall wheatgrass (Thinopyrum ponticum L. cv. Dundas), and veldt grass (Ehrharta calycina Sm. cv. Mission) were tested in a controlled environment on the growth and nutrition with the microbial consortium inoculant and rock mineral fertiliser.Results: Veldt grass produced the highest shoot and root growth, while tall fescue yielded the lowest. Rock mineral fertiliser with or without microbial consortium inoculant significantly increased root and shoot biomass production across the grass species. The benefit of microbial consortium inoculation applied in conjunction with rock mineral fertiliser was significant regarding shoot N content in tall wheatgrass, cocksfoot and tall fescue. Shoot P and K concentrations also increased in the five grass species by microbial consortium inoculation combined with rock mineral fertiliser in comparison with the control treatment. Arbuscular mycorrhizal (AM) colonisation decreased with rock mineral fertilisation with or without microbial consortium inoculant except in cocksfoot.Conclusions: The response to microbial consortium inoculation, either alone or in combination with rock mineral fertiliser, was plant species‐dependent, indicating its potential use in pasture production.

Cogon grass biochar amendment and Panicum coloratum planting improve selected properties of sandy soil under humid lowland tropical climatic conditions

Biochar amendment improves the physical, chemical and biological characteristics of different soil types under different climatic and environmental conditions. In this study, effects of biochar or live pasture plants existing alone or co-existing on selected soil properties of sandy loam soil under humid lowland tropical climatic conditions were investigated. The changes measured in the amended soil, with or without plants, were compared to the unamended and unplanted soils. Biochar amendment with or without pasture improved moisture retention, lowered bulk density, increased pH and kept the electrical conductivity within ranges conducive for pasture growth. Generally, contents of all the nutrients increased following biochar amendment, however pasture establishment without amendment resulted in depletion of available potassium and magnesium. Under all treatment conditions, soil organic carbon and soil organic matter were significantly depleted. Cogon grass is invasive under all land use systems and contributes to greenhouse gas emissions through slash-and-burn. Using biomass from the grass instead of burning would mitigate CO2 emissions from the tropics.

Light Interception and the Growth of Pastures under Ideal and Stressful Growing Conditions on the Allegheny Plateau.

Pasture-based livestock production is impacted by management and weather. In pastures, there is conflict between leaf retention for plant growth and leaf harvest for animal nutrition. Defoliated pastures with low light interception (LI) may have a low forage growth rate (FGR), while excessive growth shades leaves, reducing FGR and resulting in an S-shaped regrowth curve. To optimize production, it is best to keep FGR linear. Three studies were conducted to evaluate the impact of management and weather on FGR. Replicated pastures were used to measure FGR when grazed from 25 to 10 cm and allowed to regrow. The impact of alternative defoliation timings and intensities on FGR were studied using clipped treatments at three recovery intervals and two stubble heights. Variability in FGR was studied using a field validated plant growth model. Of the 24 growth periods studied, two displayed exponential, 12 linear and 10 linear-plateau growth. There was no effect of FM on growth curve form. In May and June, LI increased with canopy height, up to 0.93. Stubble height and days of growth impacted FGR with an interaction. There was no treatment impact on root density. Weather caused variation in FGR. A low FGR risk occurs at high elevations; greater risk occurs east of the plateau.

Parameterization of the APSIM model for simulating palisadegrass growth under continuous stocking in monoculture and in a silvopastoral system

Sustainable intensification of livestock production systems has become a global demand. In silvopastoral systems, contrasting shading levels caused by the presence of trees interferes in the productive responses of the pasture under grazing. The environment in which plants develop in a pasture canopy is dynamic and complex due to the nature of soil-plant-animal interactions. These dynamic aspects can be rationalized, evaluated, and explained using mathematical modeling. The objective of the present study was to parameterize the APSIM-Tropical Pasture model to simulate palisadegrass [Brachiaria brizantha (Hochst A Rich) Stapf, syn. Urochloa brizantha] growth under continuous stocking and variable stocking rate, in a full sun system and in contrasting shading conditions of a silvopastoral setting with eucalyptus (Eucalyptus grandis W. Hill ex Maiden × Eucalyptus urophylla S. T. Blake). Trees were planted in triple-row groves, with three groves per 2-ha silvopasture area. The spacing between groves was 30 m, and tree density was 135 ha−1, in East-West orientation. The data used to calibrate and validate the model were collected in a 36-month experiment with full sun and shade treatments of the silvopastoral setting in Sinop, MT, Brazil. Live forage mass estimates had coefficient of determination varying between 0.76 and 0.94, Willmott agreement index ranged from 0.93 to 0.96, and root mean square error between 275 and 610 kg DM ha−1. The APSIM-Tropical Pasture model can simulate Marandu palisadegrass growth under continuous stocking with variable stocking rate, but improvements are needed to better simulate the effect of N fertilizations in different periods on growth. The model can simulate pasture growth under shading levels but our simulations did not consider competition for soil moisture, which should be considered in the future, since it can be an important factor for other silvopastoral designs or microclimatic conditions.

Crecimiento de los pastos Cayman y Cobra en diferentes niveles salinos de NaCl, en invernadero

Los suelos salinos afectan el crecimiento y rendimiento de los pastizales y disminuyen la disponibilidad de forrajes para la alimentación animal. Objetivo: Evaluar la emergencia, crecimiento y producción de biomasa de los pastos Cayman (BR/1752) y Cobra (BR/1794) en condiciones de estrés salino inducido por la sal NaCl a siete niveles de conductividad eléctrica (CE): 0, 2, 4, 6, 10, 12 y 15 dS m-1. Metodología: en invernadero, se establecieron macetas experimentales con agrolita, sembradas a una densidad de 25 semillas por maceta para evaluar la emergencia; posteriormente se realizó un aclareo para dejar tres plantas por maceta en un diseño completamente al azar. El riego consistió en reponer el agua perdida por evapotranspiración, mediante el suministro de agua destilada. El experimento abarcó un periodo de 60 días durante los cuales se determinó la altura y el diámetro del tallo, número de hijuelos, el número de hojas, la longitud de raíz y producción de biomasa. Los resultados indican que al aumentar la conductividad eléctrica de las soluciones salinas, ambos pastos disminuyeron de manera diferencial el porcentaje de emergencia, la altura y el diámetro del tallo, el número de hijuelos y el número de hojas, con una disminución en la producción de biomasa de las plantas, más pronunciado en pasto Cayman que en pasto Cobra. Entre cultivares se presentaron diferencias de tolerancia; ya que en el pasto Cayman esta disminución se produjo a CE ≥ 10 dS m-1, mientras que en el pasto Cobra la producción de biomasa fue afectada signif icativamente (P = 0.05) a partir de CE ≥ 12 dS m-1.

The Impact of Herbicide Application and Defoliation on Barley Grass (Hordeum murinum subsp. glaucum) Management in Mixed Pasture Legumes

Barley grass (Hordeum murinum subsp. glaucum.) is an annual weed associated with grain revenue loss and sheep carcass damage in southern Australia. Increasing herbicide resistance led to a recent investigation into effective integrated weed management strategies for barley grass in southern Australia. Field studies in Wagga Wagga, New South Wales (NSW) during 2016 and 2017 examined the effect of post-emergent herbicide applications and strategic defoliation by mowing on barley grass survival and seed production in a mixed legume pasture. Statistically significant differences between herbicide-only treatments in both years showed propaquizafop to be more than 98% effective in reducing barley grass survival and seed production. Paraquat was not effective in controlling barley grass (58% efficacy), but led to a 36% and 63.5% decrease in clover and other weed biomass, respectively, after 12 months and increased lucerne biomass by over three-fold after 24 months. A single repeated mowing treatment resulted in a 46% decline in barley grass seedling emergence after 12 months and, when integrated with herbicide applications, reduced other weed biomass after 24 months by 95%. Resistance to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides observed in local barley grass populations led to additional and more focused investigation comparing the efficacy of other pre- and post-emergent herbicides for barley grass management in legume pastures. Haloxyfop-R + simazine or paraquat, applied at early tillering stage, were most efficacious in reducing barley grass survival and fecundity. Impact of defoliation timing and frequency on barley grass seedlings was also evaluated at various population densities, highlighting the efficacy of repeated post-inflorescence defoliations in reducing plant survival and seed production. Results highlight the importance of optimal environmental conditions and application timing in achieving efficacious control of barley grass and improving pasture growth and biomass accumulation.

Simulated seasonal responses of grazed dairy pastures to nitrogen fertilizer in SE Australia: N loss and recovery

Evidence from farm level studies indicates that there is potential to improve nitrogen (N) fertilizer efficiency of Australian dairy farms. Increasing N fertilizer application rates to drive pasture dry matter production beyond an agronomic or economical optimum has the potential to result in detrimental environmental outcomes. Our study, using the biophysical whole-farm systems model DairyMod, modelled a range of N fertilizer rates on total N loss for five dairy sites through south-eastern Australia, using 18 years of historical climate. Nitrogen accumulation in plant biomass and soil N accumulation within and below the rootzone were estimated. Total N loss, in the form of volatilization, leaching, runoff and denitrification lost to the environment were also estimated. The reduction in N fertilizer inputs required to achieve 90% of relative yield (Y90), relative to maximum pasture production (Ymax), was > 50% across all sites and seasons. The associated reduction in total N loss when fertilizer was reduced from Ymax to Y90, varied between 34% and 74%, depending on site and season. Nitrogen recovery (proportion of N recovered in biomass relative to N fertilizer applied) exceeded 100% with lower N fertilizer rates (< 30 kg N ha-1 month-1) for most sites and seasons. Demand for N was high during spring due to high pasture growth and this was supported via N mineralization and legacy N build-up in winter. Nitrate leaching risk was highest in winter for the four temperate sites and autumn at the subtropical site. This study demonstrated the benefits of developing site and seasonal-specific N fertilizer best management practice guidelines that are both economical and environmentally beneficial. When considering whether to add more fertilizer, the value of additional pasture production needs to be weighed up against environmental N losses and the cost of additional N fertilizer to achieve this. The relationship between seasonal soil and climatic conditions and N loss and recovery were also examined for one rainfed site. As this study does not consider the externalities associated with N loss, recommendations need to be considered and amended in the context of location specificity and seasonal climatic conditions.

Probing Soil Electrochemistry: Electrochemical Characterization of Soil Via a Faradaic Approach

Soil is a vital component that holds together the Earth’s ecosystem. It plays an active role in biological events, hydrologic (water) cycle and behaves as a sink-source system for greenhouse agents (gases). More so, soil directly impacts growth of plants, crops and other vegetation. Commercially, soil quality determines the yield and type of farmland-wherein it is essential to have thorough information about soil parameters that is synchronized in terms of geological location (space) and period (time) due to variations associated with global change and land use. Implementation of soil sensors would be fundamentally beneficial to characterize the soil parameters in a local as well as global environmental-impact standpoint. Assessment of these parameters in soil samples in farm setting facilitates quantification and recording of its inherent physical and biochemical characteristics. Sufficient levels of soil nutrients is required for sustainable agricultural practices that typically exists as crop yield, pasture growth, etc. Currently, soil sampling and evaluation methods involve destructive and intrusive approaches to collect and then subsequently test the soil samples. Among this-Combustion method is one of the most widely sought after techniques to look at soil anatomy. Even with the upcoming research breakthroughs in non-destructive approaches like spectroscopy and tomography based models, there is a barrier in-terms of equipment complexity and availability as well as high costs and high logistical overhead. Therefore a sensing based ‘bottom-up’ approach is proposed in this study to probe soil matter and nutrient content. Soils are known to be dynamic systems under natural conditions and implementation of an integrated electrochemical and analytical chemistry methodology offers the added advantage of evaluating soil properties on-demand and in situ. Another main advantage of an electrochemical-analytical approach and the novelty of the proposed platform lies in the ability to profile soil at an interfacial level using a probe system and characterize the matrix in order to provide information in terms of various physico-chemical phenomena occurring at the electrode interface and correlate that to useful data that helps to understand soil fertility and bio-availability of nutrients for plants and other vegetation at the field level. There are a wide number of redox systems present in soil that exist in reduced state under ideal conditions (submerged). Soil is known to contain considerable amounts of these reducing substances as a function of organic matter content. In this work, faradaic measurements are utilized to determine threshold changes in soil electrochemical activity due to presence of various redox active substances present in the matrix. From preliminary data (Fig.1) and literature studies, there seems to be a high-correlation between electrochemical activity and presence of active substances that contribute to the soil-nutrient cycle which in turn differs in terms of various soil types. Therefore, probing these parameters could give further insight as to what in particular in the soil matrix contributes to the overall properties of soil type of a specific region. Results from this experimental question is used to track if confident deductions can be made with respect to constituency of soil matrix, assessing soil type, bulk density (BD), cation exchange capacity (CEC), electrical conductivity (EC), and electrochemical activity as a function of spatial and depth changes among other parameters. Figure 1

Estimation of Productivity in Dryland Mediterranean Pastures: Long-Term Field Tests to Calibration and Validation of the Grassmaster II Probe

The estimation of pasture productivity is of great interest for the management of animal grazing. The standard method of assessing pasture mass requires great effort and expense to collect enough samples to accurately represent a pasture. This work presents the results of a long-term study to calibrate a Grassmaster II capacitance probe to estimate pasture productivity in two phases: (i) the calibration phase (2007–2018), which included measurements in 1411 sampling points in three parcels; and (ii) the validation phase (2019), which included measurements in 216 sampling points in eight parcels. A regression analysis was performed between the capacitance (CMR) measured by the probe and values of pasture green matter and dry matter (respectively, GM and DM, in kg ha−1). The results showed significant correlations between GM and CMR and between DM and CMR, especially in the early stages of pasture growth cycle. The analysis of the data grouped by classes of pasture moisture content (PMC) shows higher correlation coefficients for PMC content &gt;80% (r = 0.775; p &lt; 0.01; RMSE = 4806 kg ha−1 and CVRMSE = 28.1% for GM; r = 0.750; p &lt; 0.01; RMSE = 763 kg ha−1 and CVRMSE = 29.7% for DM), with a clear tendency for the accuracy to decrease when the pasture vegetative cycle advances and, consequently, the PMC decreases. The validation of calibration equations when PMC &gt; 80% showed a good approximation between GM or DM measured and GM or DM predicted (r = 0.959; p &lt; 0.01; RMSE = 3191 kg ha−1; CVRMSE = 23.6% for GM; r = 0.953; p &lt;0.01; RMSE = 647 kg ha−1 and CVRMSE = 27.3% for DM). It can be concluded that (i) the capacitance probe is an expedient tool that can enable the farm manager to estimate pasture productivity with acceptable accuracy and support the decision-making process in the management of dryland pastures; (ii) the more favorable period for the use of this probe in dryland pastures in a Mediterranean climate, such as the Portuguese Alentejo, coincides with the end of winter and beginning of spring (February–March), corresponding to PMC &gt; 80%.

Dry matter decomposition and potassium cycling in no-till integrated crop-livestock systems: the effects of tree shading and nitrogen fertilization

In integrated crop-livestock systems (ICLS), understanding residue dynamics is crucial to synchronize nutrient release from pasture litter to cash-crop nutrient demands and overcome potential deficiencies using suitable fertilization strategies. The present study evaluated how the inclusion of trees and N availability affected the release rates of K from pasture (black oat + ryegrass) residues to the subsequent maize crop in a no-till ICLS. The experimental design was randomized blocks with treatments set up in split-plots with three replications. Main plots were systems (crop-livestock only and crop-livestock with trees) and sub-plots N levels (90 and 180 kg N ha-1). Litter decomposition and K release from pasture residues were assessed using litterbags, which were installed at maize sowing, for retrieval at 8, 15, 30, 60, 90, 120, 150, and 165 days of incubation. Regardless of N level, shade of 7-year-old trees reduced pasture residue (-30%). Tree residues were unable to offset the shading effect on pasture growth. A faster dry matter decomposition was observed in treeless treatment and with 180 kg N ha-1, with a half-life ranging from 14 to 38 days. Despite no changes in K-release dynamics among treatments, total K released was significantly higher for treeless system (61 kg K ha-1) than in system with trees (40 kg K ha-1), due to changes in the initial amount of residue. These results must be taken into account in fertilization practices. Therefore, a few feasible silvicultural interventions should be considered to avoid losses in soil cover, maximizing nutrient cycling benefits.