Agriculture & Soil
Growing systems, soil science and what field trials actually show.
- 5 min
A Chickpea Variety Trial in South-western Oromia: What It Shows and What It Doesn't
A field experiment at two districts in the Buno Bedele Zone compared six improved Kabuli chickpea varieties across the 2023 and 2024 main cropping seasons. Varieties differed significantly in flowering time, maturity, pods per plant, seeds per pod, hundred-seed weight and grain yield, but not in plant height. Koka gave the highest grain yield at 1568.04 kg per hectare and Hora the lowest at 865.83 kg per hectare. The authors recommend Koka and Habru for the area, though the abstract reports no per-site or per-season yield breakdown and no disease or insect data.
- 6 min
Foliar urea lifted rainfed castor yield in one Indian trial. The nitrogen arithmetic is harder to read.
A three-season field experiment on rainfed castor compared eight nitrogen management modules. The best performer applied the full recommended basal nitrogen rate and then added 2% urea foliar sprays at 30 and 60 days after sowing, reaching 1,546 kg seed per hectare. Foliar urea beat nano urea at the rate tested. The trial does not show that foliar feeding can replace soil nitrogen, because the winning treatment added nitrogen rather than substituting it.
- 5 min
Mustard Seed Cake Beat NPK in One Season of Spring Rice. That Is One Season.
A single-season field trial in eastern Nepal compared six amendments and an unfertilized control on spring rice. Mustard seed cake at 6 tonnes per hectare was the only treatment to significantly beat all others, reaching 5.07 t/ha of grain. Farm yard manure, goat manure, poultry manure, vermicompost, recommended NPK and the control all yielded statistically the same, which the authors attribute to residual soil fertility at the site. The result is one season, one site, one variety, and the authors call for multi-season confirmation.
- 5 min
Biochar in vineyards: the carbon storage holds up, the yield gains do not
A 2026 integrative review of vineyard biochar trials found the strongest evidence is for carbon persistence: the inert fraction was unchanged after 15 years and 65 to 89 percent remained after 100 years. Yield gains of 16 to 67 percent appeared only in three Tuscan vineyards on acidic, carbon-poor, non-irrigated soils, while eight other site comparisons showed no significant response. Nitrous oxide and methane reductions are not robust at field scale and have not been detected in vineyards. The review calls long-term microbial effects, economic viability and large-scale carbon farming plausible but poorly documented or speculative.
- 5 min
Ten years of no-till moved carbon in the topsoil, not the subsoil
A ten-year field trial on a Haplic Plinthosol in South Africa compared no-till with conventional tillage, four crop rotations, residue retention versus removal, and three soil depths. No-till raised soil organic carbon in the top 20 cm, and rotation plus residue retention increased particulate organic matter down to 40 cm. Between 20 and 60 cm the authors report limited change and call for longer monitoring before expecting substantial subsoil carbon gains. The result is one site, one soil type, one sampling season.
- 5 min
A cotton-waste hydrogel lifted corn and cotton yields in a saline Kazakh field trial. One season is one season.
A field trial in southern Kazakhstan applied a superabsorbent polymer made from cotton linter to corn and cotton grown on salt-affected soil under irrigation. Yields of both crops rose steadily as the polymer rate increased from 0 to 50 kilograms per hectare, and irrigation water productivity roughly doubled. The trial ran for one season at one site with four blocks. The authors state that multi-season trials, soil-water monitoring, economic analysis and full polymer characterization are still needed.
- 5 min
One Trial, One Grass, One Place: What Piggery Sludge Did for Signal Grass in Papua New Guinea
A single field trial in the humid lowlands of Papua New Guinea applied solid piggery sludge at 0, 2.5, 5 and 10 tonnes per hectare to signal grass and harvested after six months. Yields and soil nutrient measures rose sharply at the two highest rates, and the authors recommend 5 tonnes per hectare. The same trial found copper, lead, cadmium and chromium above standard permissible limits, and reported metal accumulation in soil and biomass. With one site, one season and no mineral fertiliser comparison, the yield result is a lead worth following, not a settled practice.
- 5 min
More nitrogen lifted jute fibre yield, up to 140 percent of the recommended dose, in one field, in one season
One field experiment at Kishoreganj, Bangladesh, tested six nitrogen rates on jute variety BJRI Tossa Pat-8 over one growing season. Fibre yield peaked at 140 percent of the recommended dose (112 kg per hectare) and fell at 160 and 180 percent. Plants kept growing taller and leafier at the highest dose, but harvest index dropped, meaning a smaller share of the plant ended up as fibre. The result rests on one site, one season and one variety.
- 5 min
A Pot Trial in Telangana: Rice Microbes and Nitrogen Under Drought
One 2024 pot experiment in Warangal, India crossed six microbial inoculation treatments with two soil moisture levels in rice. A tripartite bacterial consortium given with 75 percent of the recommended nitrogen dose preserved rhizosphere diversity, sustained nitrogen-cycling enzyme activity and improved nitrogen use efficiency and grain yield relative to an uninoculated control under water deficit. The authors say the result needs open-field confirmation. No effect sizes, replication counts or comparisons against a full-rate nitrogen control appear in the abstract.
- 6 min
One field, one season: what the manure-depth trial actually shows
A single-season field experiment in Jilin Province, China, tested three manure rates, three application depths and two placement methods on saline silty loam planted to corn. It found that 40 tonnes per hectare lowered electrical conductivity and pH relative to control plots, and that deeper, mixed application lowered conductivity further. The study measured only electrical conductivity, pH and bulk density, after one harvest, at one site. It reports no yield, no second year and no mechanism.
- 5 min
A Quarter Less NPK, Same Maize Yield, in One Field for One Season
A single field trial in Bengkulu, Indonesia tested whether fermented oil palm empty fruit bunch liquid could substitute for mineral NPK on hybrid maize. Replacing 25 percent of the NPK dose held grain yield and nitrogen uptake; replacing 50 percent held yield but cut nitrogen uptake by 13 percent; replacing 75 percent cut yield. The trial ran one season at one site with four replications and reported no cost analysis, so the economics that motivated the study remain untested.
- 5 min
Manure Cut Fertilizer Needs in a Shallot Trial. One Season, One Field, One Soil.
A single-season trial on an acid Ultisol in Bengkulu, Indonesia, tested composted cattle manure at 10 tonnes per hectare combined with 100, 75, 50, 25 or 0 percent of the recommended NPK rate, against a full-NPK reference with no manure. Manure plus 75 percent NPK gave the highest fresh bulb yield, 18.3 percent above the reference, and manure plus 50 percent NPK matched the reference while cutting storage weight loss from 22.2 to 15.1 percent after eight weeks. The trial was not replicated across sites or seasons, and the abstract reports no mechanism for the storage effect.
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