Biochar Enriched with Buffalo Slurry Improved Soil Nitrogen and Carbon Dynamics, Nutrient Uptake and Growth Attributes of Wheat by Reducing Leaching Losses of Nutrients

The present investigation was conducted to understand the role of enriched biochar on soil nitrogen and carbon dynamics, leaching losses of nutrients, and growth attributes of wheat. Buffalo slurry (BS) was used to enrich the biochar for 24 h and 2% biochar (SB) or enriched biochar (SEB) was used. Enrichment of biochar with BS as SEB improved the C and N contents of biochar by 33–310% and 41–286% respectively. The application of biochar (SB) and enriched biochar (SEB) reduced the net nitrification by 81% and 94%, ammonification by 48% and 74%, and carbon dioxide by 50% and 92% respectively as compared to control. The leaching losses minerals i.e., C (by 30%), N (by 125%), P (by 50%), K (by 82%), Na (by 9%), Ca (by 24%), and Mg (by 12%) was decreased in SEB treatments compared to control. The soil enzyme activities, microbial biomass (MBC and MBN), wheat agronomy, soil bulk density and soil pore density, mineral uptake from the soil, and mineral contents in the plant body were improved in the SEB as compared to SB and control treatments. Our results revealed that the biochar enrichment process could improve the C and N storage in the soil reservoir and lower the environmental risks to soil and water.

Soil Application of Zeolite Affects Inorganic Nitrogen, Water Soluble and Exchangeable Potassium

An incubation study was conducted at college of agriculture, rajendranagar, PJTSAU to evaluate the influence of zeolite application on inorganic nitrogen, water soluble and exchangeable potassium in soil. Clinoptilolite Zeolite was fully mixed with soil (7.5 t ha-1) at the start of the experiment. Nitrogen was applied to soil through urea (200 kg ha-l). The experiment was conducted for 35 days and soil was analyzed for inorganic nitrogen, water soluble and exchangeable potassium at weekly intervals i.e., 1, 7, 14, 21, 28, 35 days of incubation. The results indicated that the treatment with zeolite application showed significantly higher ammoniacal nitrogen from day 1 (136.54 mg kg-l) to day 35 (38.71 mg kg-l) as well as nitrate nitrogen (day 1 – 59.13 mg kg-l; day 35 – 130.13 mg kg-l). Similarly water soluble (day 1 – 92.21 kg ha-l; day 35 – 103.13 kg ha-l) and exchangeable potassium (day 1 – 363.69 kg ha-l; day 35 – 393.94 kg ha-l) was also significantly higher in zeolite applied treatments. Thus, mixing of zeolite into soil improves inorganic nitrogen through reducing leaching losses and also improves water soluble and exchangeable potassium.

Soil nitrogen and water management by winter-killed catch crops

Improving N cycling in agroecosystems is one of the key challenges in reducing the environmental footprint of agriculture. Further, uncertainty in precipitation makes crop water management relevant in regions where it has not been necessary thus far. Here, we focus on the potential of winter-killed catch crops to reduce N leaching losses from N mineralization over the winter and soil water management. We compared four single catch crops (white mustard, phacelia, Egyptian clover and bristle oat) and a fallow treatment with two catch crop mixtures with 4 and 12 plant species (Mix4 and Mix12). High-resolution soil mineral N (Nmin) monitoring in combination with modelling of spatiotemporal dynamics served to assess N cycling under winter-killed catch crops, while soil water was continuously monitored in the rooting zone. Catch crops depleted the residual Nmin pools by between 40 and 72 % compared to the fallow. The amount of residual N uptake was lowest for clover and not significantly different among the other catch crops. Catch crops that produce high N litter materials, such as clover and mustard leaves, showed an early N mineralization flush immediately after their termination and the highest leaching losses from litter mineralization over the winter. Except for clover, all catch crops showed Nmin values between 18 and 92 % higher on the sowing date of the following maize crop. However, only Mix12 was statistically significant. Catch crops depleted the soil water storage in the rooting zone during their growth in autumn and early winter, but preserved water later on when their residues cover the ground. The shallow incorporation of catch crop residues increased water storage capacity during the cropping season of the main crop even under drought conditions. Hence, catch cropping is not just a simple plant cover during the winter but improved the growth conditions for the following crop at decreased N losses. Mixtures have been shown to compensate for the weaknesses of individual catch crop species in terms of nutrient capture, mineralization and transfer to the following main crop as well as for soil water management. Detailed knowledge about plant performance during growth and litter mineralization patterns is necessary to make optimal use of their full potential.

Very Low Nitrogen Leaching in Grazed Ley-Arable-Systems in Northwest Europe

High input dairy farms that are located on sandy soils in northwest Europe are predisposed to substantial nitrate leaching during a surplus of winter precipitation. Leys within integrated crop-livestock systems play an important role in soil fertility, soil C sequestration and soil N mineralization potentials. Therefore, leys are a feasible option that can be utilized to reduce local N losses to the environment, especially following maize grown for silage. We hypothesize that grass-clover leys ensure low nitrate leaching losses even when grazed intensively. The extent to which NO3-leaching occurred across seven different pasture management systems in terms of their sward composition, cutting, grazing, fertilization and combinations thereof was investigated in integrated animal-crop grazing systems over three winter periods (2017/2018, 2018/2019 and 2019/2020). The observed grazed systems were comprised of cut-used- and grazed grass-clover swards (0, 1 and 2 years after establishment following cereals), a catch crop grazed late in the year as well as a cut-used permanent grassland for comparison. Overall, all treatments resulted in nitrate leaching losses that did not exceed the WHO-threshold (25 mg nitrate/L). The highest level of NO3-leaching was observed in the catch crop system and the lowest in cut-used permanent grassland, with NO3-N losses of 19.6 ± 5.3 and 2.1 ± 0.3 kg NO3-N ha−1 year−1. Annual herbage yields were in the range of 0.9 to 12.4 t DM ha−1 and nitrogen yields varied between 181 ± 51 and 228 ± 66 kg N ha−1 during the study period. The highest herbage-N-yields were observed from the 1- and 2-year-old grass-clover leys. The highest N-field-balance was observed for the grazed leys and the lowest for the cut-used permanent grassland. However, no correlation was found between the highly positive field-N-balance and the amount of NO3-leached. This indicates a high N carry-over from grass-clover swards to the subsequent cash crop unit instead of increasing the risk of groundwater contamination from grazed leys in integrated animal crop-systems and underlines the eco-efficiency of dairy farming based on grazed ley systems.

Phosphorus availability and leaching losses in annual and perennial cropping systems in an upper US Midwest landscape

Excessive phosphorus (P) applications to croplands can contribute to eutrophication of surface waters through surface runoff and subsurface (leaching) losses. We analyzed leaching losses of total dissolved P (TDP) from no-till corn, hybrid poplar (Populus nigra X P. maximowiczii), switchgrass (Panicum virgatum), miscanthus (Miscanthus giganteus), native grasses, and restored prairie, all planted in 2008 on former cropland in Michigan, USA. All crops except corn (13 kg P ha−1 year−1) were grown without P fertilization. Biomass was harvested at the end of each growing season except for poplar. Soil water at 1.2 m depth was sampled weekly to biweekly for TDP determination during March–November 2009–2016 using tension lysimeters. Soil test P (0–25 cm depth) was measured every autumn. Soil water TDP concentrations were usually below levels where eutrophication of surface waters is frequently observed (> 0.02 mg L−1) but often higher than in deep groundwater or nearby streams and lakes. Rates of P leaching, estimated from measured concentrations and modeled drainage, did not differ statistically among cropping systems across years; 7-year cropping system means ranged from 0.035 to 0.072 kg P ha−1 year−1 with large interannual variation. Leached P was positively related to STP, which decreased over the 7 years in all systems. These results indicate that both P-fertilized and unfertilized cropping systems may leach legacy P from past cropland management.